Thanks to ThyEnemy for these great tips and tricks!

Movement Techniques.

Pre-Combat
Before you can enter any kind of combat you must first make sure you know what you're going to do. There are basically three things you should choose from and then there are sub-groups that are being discussed.
The three tactics for every battle are:
- Flight
- Fight: Close-Combat
- Fight: Long-Range

Flight:
The way you should make the first choice Fight/Flight depends on factors such as shield-health, objectives, wether or not you're already fighting someone or even on weapon difference.
Note - When you choose Flight run in as much of a straight line as possible to your objective point and do so running forward, because that is the fastest way of running.

Fight:
When you have choosen to fight and you are in a situation where you can choose between Close-Combat or Long-Range choose your battle by answering the following questions:
- Did my opponent get the first shot off?
- Is my opponent weakened in any way?
- Did I already get three shots off?
- Is or will the distance between him and me get small enough for him to melee me?
- Is there other trouble for me if I walk backwards?
If you've answered these questions negative then stick with Long-Range, when you have to answer yes on one of these questions proceed to the Close-Combat section.

Fight Long-Range:
When you enter combat then either choose close-combat or long-range, then stick with what you choose or try to back away in a safe-route.

Strafe:
Strafing is the technique where you move in order while shooting to make it harder for your opponent to hit you. Strafing can be way more useful than how most people do it.
Now, because most people just go left and right and go the same distance each time, most battle rifle duels just look like mating rituals.
Rise above this!
1. You can strafe in three dimensions
2. You can vary moving distances in two of those dimensions
3. You can combine all three dimensions

Peekshooting:
When you enter a new environment you don't just want to rush in hoping noone is looking in your direction.
When you enter a room keep one of your sides covered by a wall and stay a little behind it, now scan the room horizontally on headshotlevel starting on the opposite side of where the wall is covering you. Then as you explore more of the room slowly move a little away from the wall so you can see more of the room while keeping your reticule just next to the wall covering you so that the moment when you see someone is the same moment when you shoot someone.
Note - after you got the first shot off, you can use the technique again by wall-strafing.

Wall-Strafing:
This technique works the same way as peek-shooting, but this time it isn't just about getting the first shot.
Wall-strafing is meant to annoy your opponent, because you hide away behind your wall after every shot. Just keep a wall to your side and go side to side while aiming for headshots, just pop out when you know that you can shoot again. Stay as close to the wall as you can with the first three shots, so you don't risk getting naded, with the last shot you can go a little to the back so you can make the last shot a clean headshot. Preferably take a wall to the right side of your body so your head is safe longer. This technique is also referred to as getting Karma-ed and is used a lot from Pink 2 on Midship.
Note - You can also do this in front of a fence by crouch/uncrouching.

Corners of life:
This technique revolves around certain key-points on the map that you have to discover. This is the next step in the line of Peek-Shooting and Wall-Strafing.
Now, when you look over your battle rifle, your head goes a little to the right of it, meaning that you can still fire when the right side of your body, including your head is covered by a wall. When you use such a corner aim a little to the left of the wall, then run forward and to the right to put your head even futher in the corner. If you'd see a spartan walking to the front and right, you'd see his head going even more to the right side of his gun. This is what makes the corner more effective than a plain wall.
An example: take the sniper spawn on Ivory towers and walk from there a little to the overshield side of the hall-way, now look back and use the corner on the right side of that part of the hall-way to cover your side.

Strongside Strafe:
The Strongside Strafe is a strafe that revolves around varying moving with not moving, trying to confuse your opponent by periodically stopping.
It is performed by aligning yourself to a wall (hugging the wall), move a little one way, stop, move a little more, stop again and then strafing all the way in the other direction for as long as you want.
Note - When you do this on a slanted ramp it is even more confusing, because you are using the vertical dimension as well.

Anticipation dodges:
These are two technique you should use when your opponent has got the first shot on you and you don't/can't back away so this should be your last resort.
Listen to your opponents shots and try to make a dodge move right before when you expect them to fire. You want your head to move quickly so the best way to do this is to suddenly duck. If your opponent misses you're ahead and you can finish with regular strafe techniques, but if he didn't miss remain crouched and go to the second dodge technique.
When you expect his next shot, this time uncrouch+jump. This moves your head so quickly that there really is no way for him to make another headshot.
Note - You can also crouch and uncrouch+jump inbetween two of your opponents shots, but that'd make it pretty hard to aim for your own shot.

Counter-Strafe:
Counter strafing is a technique similar to Anticipation Dodges, but instead of focussing on your opponents shots you look at his movement. Counter strafing is done by doing the opposite what your opponent does in sideways movement constantly and knowing you have to over-adjust your reticule while your opponent doesn’t. This technique is very confusing to your opponent and can be a good solid strafe technique.

Gandhi-hop:
This technique isn't originally a strafe in battle rifle battles, but rather an evasion technique to avoid getting headshotted by the sniper rifle.
The way it works is to first get away from headshot level that snipers generally use to sweep-headshot, by jumping. Then to make it even harder for snipers, keep crouching/uncrouching in the air so your head keeps bouncing.
It can be used in battle rifles when you have made a shot, jump and have to wait before you can make another shot. Your aim also won't really be off while doing this, due to auto-aim, but his aim might be off more, because you notice your crouching less on your screen, than he notices on his.

Ceiling Bounce:
The ceiling bounce is an extension of the Gandhi-hop and revolves around a glitch when the spartan body makes contact with a ceiling.
When you jump towards a ceiling, hit crouch right before you hit it. This will make you fall abnormally fast and can even throw off the auto-aim in a plasma bolt. When performed under a slanted ceiling this technique will make for a reversed slide-jump.

OgreTwitch:
With all the ways you can move in shooting-duels you need to upgrade your aim accordingly to keep up with your feet.
The OgreTwitch and SaiyanTwitch are techniques to improve your aim by just twitching your reticule into a circle. By doing this clockwise&counter-clockwise and in big and small circles while out of combat you can really keep the sense for precise aiming in your thumbs.
The difference between the OgreTwitch and Saiyan Twitch is just the size in the circles, large circles are better for keeping the feeling on how much force to use to get to the first shot, small circles are better for keeping the feeling on how little force to use to continue with the shots following.
Note - Another effect of this motion is to recalibrate your controller.

Doubleshot environmoments:
When it comes to doubleshotting you can't always let the gun do the talking, because you might not be carrying a secondary or you might fail the glitch, so do as the pro's do and let the environment and moments (hence: environmoments) do the talking. There are basically three situations in which you want to attempt a doubleshot without a secondary.
1. The first situation is when you are behind in a battle rifle duel and you want to use the doubleshot as a last resort tactic, this is a moments move.
2. The second situation requires more confidence in your doubleshots and is more of an environment move. When you are winning a duel, but you want to go to a Pre-designated location (see below) in order for you to survive before someone else picks you off. Then use a fade-away move on your last two shots and doubleshot when you are about to move behind a wall or something else that covers you.
3. This third situation is a combination of the two and is (unlike the first 2) more of a Team situation, because unlike in FFA games you will be taking cover more often, due to the pace of the game and the tactics. So the situation is where you are at your place of cover (environment) and want to fade away, because you know you won't last regularly (moment), then your third shot should be when you attempt the doubleshot while fading away.

Pre-designated location:
This technique is more of a Free-For-All strategy and focusses on where you want to be after a battle rifle duel.
This strategy works by going to your safe-place when you know during a duel that you will win. Once you know, move in a straight line to a safe location (corners and ledges) while finishing your last shot(s). The technique part here is the art of knowing where to go and knowing from which directions you might get shot while going there.

Face-on or Face-off:
Following the previous technique comes the choice what technique to use while going to your safe-place.
You can choose to face-away from the directions you might get fired from while watching your feet so your head becomes harder to hit. Or you can carefully watch the game hoping to finish someone off who is also hit, before someone notices you.
I usually recommend people to Face-off in team games and Faceon in FFA games, because FFA games end much sooner so it's not a shame to have to respawn sometime.

Weaponglitches

Easy DoubleShot: Rushed RRBX
The MeleeFire (with shots fired) as described in the 'hardest' glitches section, CAN have another use, unheared off so far.
If you rush the RRBX sequence, then your melee will just not be visible and you plain DoubleShot. HOWEVER, this sequence is so much more consistent than regular DoubleShotting.
Especially people who use boxer settings should always go Rushed RRBX.
Use - Fire the first two shots normally, finish with Rushed RRBX.
Use - Rushed RRBX YY Rushed RRBX.
Note - This glitch will also auto-reload.

MeleeFire: B,X,R or B,Y,Y,R or B,X+R
As soon as your melee has hit your opponent and the damage is done, you can cancel the rest of the animation with X and open fire again. If done optimal it will seem like a melee and shot at the same time. To be done with a full clip or using Y,Y instead of X when not. When you are in your opponents face you are best off pressing X+R at the same time, this will also MeleeFire, thus killing, but also reloads after a few seconds (Off-host).
Note - Also works with sniper (MeleeSnipe), but preferably press X before the melee hits so you are still lunging towards your opponent.
Note - When you don't have ammo to reload your battle rifle, you can keep doing B,X,R.

Double Melee: B,XB or B,YB
As soon as your melee has hit your opponent and the damage is done, you can cancel the rest of the animation with X and melee again. If you have a secondary weapon you can also press Y between melee's to switch and melee with your secondary or go for a Y,Y to melee with your primary weapon again (sword and brute shot have stronger melee's than other weapons).
Note - Combine MeleeFire with a double melee B,X,R,B for a certain death.

Quick Reload: X,YY or X,BX or X,BX+R
After a certain time in a reload animation, the weapon is reloaded, pressing Y,Y, enables you to fire again sooner. This also works to cancel the swords 'reload time' since there is a period of waiting after a swordlunge. If you don't have a secondary weapon (Y,Y is switch back and forth), then press B when the gun is reloaded to melee and X to cancel it again.
If you X,B,RX so fire at the same time with the X to cancel the melee, then you will make a meleefire that will reload automatically after 2 seconds (Off-host). With the shotgun you don't have to be at the beginning of your clip like with rifles and you can just press RX at the same time to get an automatic reload.
Note - If you press Y,Y too fast, then you do a Cancel Reload.
Note - The re-reload X,B,RX only reloads off-host and works for all rifles.
Note - The Quick Reloads&Cancel Reloads also work with Doubleshotting.

Quick Switch: Y, YY or Y,BYY or Y,BX
If you want to be the faster combo-whore after releasing a plasma bolt, just switch, melee and switch switch (or cancel melee by pressing X) and you'll be able to fire a splitsecond before you combo-opposition can.
Also Y, wait, YY works.
Note - All rifles allow you to fire straight after the Quick Switch and Quick Reload, but all heavy weapons can fire just as soon as they usually can even though the animation finished

Nade Reload: L,X or L,XXX (Off-host)
If you have shot a few rounds out of your clip already and you want to reload and shoot at the same time, then press L, then quickly press X while doing the reload animation and then just keep shooting the rounds you have left in your clip while the gun reloads at the same time.
Note - Works only when you are not host, due to communication error towards the host.
Note - When you apply this trick to the carbine you have to press X 3 times, you can keep shooting the carbine after this, because it keeps automatically reloading as long as you keep shooting.

DoubleShot: RR,X
The hardest one of all; Tap R two times in a quick succession. Sort of go half-way down your trigger. On the second shot hold the trigger down, quickly after the controller has registered the start of the holding press X in order to have the two shots burst out at the same time or rapidly following eachother. Timing and precise finger movement is crucial. You will know its succesfull when you see no reloading animation, but have a full clip again with 6 bullets less.
Note - After a succesfull DoubleShot you can not shoot straight away.

DoubleShotting (with secondary): RR,X YY (repeat)
The downside of DoubleShots are the reload time, the previous glitch takes care of that, but isn't very consistent over XBL.
By doing a Cancel Reload, which is pressing YY, you can switch to a secondary, switch back and go again without having to wait for the reload.

DoubleShotting (without secondary): B,X+R RR,X (repeat) (Off-host)
First B,XR, then fire the second shot (remember the B,XR reload is about to kick in, THEN DoubleShot, wait for the B,XR reload and quickly B,XR again so you don't have to await the RR,X reload.
You can keep shooting, because you await the reload of the first B,XR, not the RR,X reload, if you fail you can shoot like you normally would AND you don't need a secondary.
Note - The time it takes to reload from the B,X+R depends on latency, meaning on some hosts you have time to even fire a regular shot between B,XR and RR,X while on others it turns into a constant stream of shots.

MeleeFire (with shots fired): RRB,X or RRB,XB
Tap fire twice rapidly (like Suicide shot) then press B right after the second shot. The seconde shot hasn't yet come out, but is waiting to come out. Then when you press X you will see the melee hit, and the shot come out.
You CAN melee straight after (RRB,XB) thereby combining all the benefits of both DoubleMelee, MeleeFire and DoubleShot. However, if you don't press the second melee, assuming you've already killed your opponenent then the RRB,X will actually auto-reload, because you have also doubleshotted.
http://www.smg-pro.com/videos/files/2/Teaser-1.wmv

Explainatory movies

Double Nade: Charge,R,pause,L,L
When you release a plasma bolt after the pistol is charged or when another plasma weapon has overheated (Beam Rifle, Plasma Rifle) wait one second and press L,L in order to through two grenades rapidly after eachother. The best time to do this is when you see your left hand 'twitch'.

Dual Nade: L,Y,B,L (On-host)
Not to be confused, but do to be combined with the Double Nade. The Dual nade is an entirely different trick that uses the picking up and dropping of dual wieldable weapons to cancel the time intersection between grenade throws. Basically you stand on a dual wieldable weapon, holding a dual wieldable weapon, then press L to throw the first grenade, hold Y to pick up the dual wieldable weapon, B to melee and throw the weapon away and L to grenade again. With boxer settings the sequel would be L,Y,L.
Note - Combine with Double Nade for a rain of grenades.

MeleeStuck: B,X,L
When you lunge towards an opponent for the melee you can cancel the full animation in order to use the lunge towards your enemy to get a plasma grenade attached. Works best when the melee has not hit yet, since you're still moving towards him.

Overheat nade: Charge,R,Y,L
When you release a plasma bolt after the pistol is charged and released you can hit Y and L quickly after eachother. What will happen is that the grenade will fly without its throwing animation. Helps if you missed the plasma shot because your opponent goes behind a wall. After the grenade is thrown there is a small time you can not shoot, but doing a cancel reload (Y,Y) fixes that.

Instant death: RR,Y,B
Stand in front of your opponent and aim at his/her head, then by pressing R,R,Y,B quickly you will first fire one shot, switchmelee and fire the second shot. The melee is to be pressed when you see the secondary weapon model. Benefit to regular MeleeFire is that you can have shots fired and you fire one shot more.
Note - You do not want to run forward while getting in range for the melee, because then you will have the second shot hitting you in the back of your head.

Suicide shot: RR,Y (secondary weapon)
This is a technique that can help you get out of a bad spawn without losing a point. When you press RR,Y and move forward the following happens. You will fire one shot, then switch to your other weapon and then fire another shot. If you moved forward during the button sequence, the second burst will hit you, because it will still come from the place where you pressed the second R.
Note - MLG prohibits this

Map Weapon Respawn Time

Lockout
Sword** 0:50
Sniper Rifle** 1:16

Ivory Tower
Sniper Rifle 2:00 (This timer starts as soon as it has been picked up off spawn)
Sword** 0:30
Rocket Launcher** 0:30
Overshield 1:23

Beaver Creek
Rocket Launcher** 0:30
Sniper** 0:30
Overshields 1:00

Warlock
Active Camo 1:10

Sanctuary
Plasma Pistol** 1:30
Energy Sword** 2:00
Sniper** 2:00
Midship
Sword** 0:30

This time is doubled for MLG Settings

All you need to know about controller settings

Sensitivity
In my experience Sensitivity is all about what feels good to you, not the ogres. If you used the default sensitivity since day one of your halo career you are most likely comfortable with that. The more comfortable you are with your sensitivity the better you will be able to aim. When you change your sensitivity you will have to get used to it obviously and when you are getting to know the new found number your aim WILL be off because your brain is used to you pressing the stick a certain amount and the aimer on the screen move a certain amount.

The higher the number the faster it moves with less force. This COULD be an advantage because you are going to be able to move to targets quicker. BUT, If you aren't able to control the reticule with 10 sensitivity with as much precision as you can with 3 sensitivity then you won't be able to kill them as fast. So sure, you could start shooting them faster but when they are strafing you might accidently move past their head thus causing you to have to shoot more. If you are able to control 10 sensitivity then the more power to you!

Also, as bradddddd helped me remember, often times you will have the upperhand in a melee battle when you have a higher sensitivity because you can react faster to their movements. So if someone jumps behind you and you are on 1 sensitivity, you will die. If you are using 10 sensitivity then you might be able to turn around quickly and kill someone.

In conclusion, higher sensitivities do have advantages, as well as lower sensitivities, but finding a sensitivity where you can control your aim perfectly would in most cases be more important. Just pick what feels the best to you and experiment. You will find the right one for you.

Button Layout
This CAN and will change the way you play and has pros and cons. The thing with changing your button layout is it changes which buttons do what.

Here is an example of why it can be beneficial to change your button layout.

The layout Green thumb changes these buttons.
Melee on default- B button
Melee on Green thumb- Pressing in right thumbstick.
Zoom on default- Pressing in right thumbstick.
Zoom on Green thumb- Pressing B.

This slight change in button functions can drastically change the way you play.

Advantage of Green thumb in this case:
If you play with Green thumb, you would know you often have the upper hand when fighting close range because you don't have to move your thumb to press the B button in order to melee saving you some time and effort. This can make all the difference in whether or not you come out on top. Having this change in button functions enables you to aim with your right thumbstick and melee at the same time which also decreases your chance of missing your melee. Green thumb wins in the close range category.

Advantage of Default in this case:
Default has the ability to aim and zoom in at the same time. They can accomplish jump sniping a LOT easier than people who use Green thumb. In turn, during a sniping battle with people that are in generally the same skill level, the default player would have a greater chance of winning because of the fact that they can aim while zooming. If you play green thumb you often find yourself walking around zoomed in quite a bit when you have the sniper, just because of the fact that you can't press b and aim your thumbstick and pull the trigger in time to kill someone before they kill you most of the time. So Default wins in the sniping category.

Another example except with boxer this time.
The layout Boxer changes these buttons:
Melee on Boxer - Left trigger
Throw a Grenade on boxer- B button
Melee on Default- B button
Throw Grenade on Default- Left Trigger

Advantage of Boxer in this case:
With boxer you can melee and aim as well. You can melee quite a bit faster than the other layouts. So like greenthumb you will have the upperhand in close range battles. Also another advantage is you can still zoom as you do with default, however on green thumb you cannot.

Advantage of Default in this case:
Default users will be able to aim their grenades with more precision then a boxer user. They will be able to aim and throw a grenade with little or no delay. People that use boxer however, must move their thumb from the thumbstick to the B button in order to throw the grenade. This inhibits their ability to aim their grenades with a precision.

Weapon glitches and the optimal settings for them.
Default
Really doesn't have any advantadges in this category.

Green Thumb
Green Thumb enables you to aim and melee at the same time with the same joystick. This enables you to actually aim your Melee cancel fires, and your melee cancel melees (also known as BXR/BXB).

Boxer
Same deal as Green Thumb. Might be slightly harder to do the grenade reload because the B is used as the grenade button.

Claw
The Claw is an unconventional way of positioning your fingers onto the controller. This is easiest to do on the duke controllers, some say.

The basic idea of how do do this is positioning your fingers so that your right hand's index finger presses the primary buttons(a,b,x,y). So every finger would be where it is normally except instead of pushing the right trigger with your index finger or resting your index finger on the end of the controller(which you would do if you pull the trigger with your middle finger.).
Again it goes like this-

Right hand
Thumb- On Right joystick
Index finger- On primary buttons ready to press them
Middle finger- On the right trigger
Rest of fingers- at rest

By doing this you are enabling yourself to press those buttons without moving your thumb. This could quite possibly be the best way to manuever through button presses because if you think about it, there really is no downside. However, some people find it quite hard to get their index finger accustomed to being in that position. If you can get it to happen comfortably then you will not need to change your control settings because you have to move your fingers to press buttons. If you do this there will be no noticable delay between button functions.

The prime example of someone using the claw is Walshy. He is known for the claw

Note: There are many variations of this.

Vibration Pros:
-Keeps you more aware of when you are under attack
-feels good if positioned the right way.

Vibration Cons:
-Some say it messes your AIM up by vibrating your fingers and screwing up their movement
-Can be quite annoying

You should be able to adjust your settings as you see fit to your playing style and aiming ability. These kinds of things can change over time and most likely will. So, play around a bit with all the sensitivities and button layouts and see what works best for you, dont ask what the pros use because as you can see they all use different settings and using one pros settings will not help you get anywhere in this game.

A Practical Guide To Technical Sniping

If you are the best sniper out there, you probably don't need to be reading this. This guide is for people who want to learn to snipe reliably, without compromising the emphasis that they put on the rest of their game. Lets face it. As nice as it is to have skills with a sniper. They don't exactly come in handy on Midship or Warlock. But with my methods, you will be able to reliably generate kills, and provide "Good" cover with the snipe.

There are those lucky people that pick up a sniper rifle, say hmmm what does this do? They squeeze the trigger a few times, and say "Oh. It shoots heads. Sweet!" I was not one of those people. Weather they know it or not, there is a reason that they have success. There are methods to sniping. People that are "Natural" snipers, are simply people that fell into these methods initially, often without knowing how or why they were successful.

Anticipation
Anticipation is the ultimate weapon of the sniper. You drastically increase your chances of hitting someone if you can predict where they will apear. This will make the difference between the guy stepping out, and dying without knowing what hit him, and him stepping out and quickly overwhelming you with his BR.

Know your teammates positions. Know where you don't see the. Use your logic to guess where they will be moving. People usually don't expose themselves for long, when they know you have a snipe. Chances are that you won't be able to respond, and accurately hit your mark, if you are just "looking around" waiting for something to present it self. Use absolutely everything available better anticipate your enemies movements. Gunfire, Little Red X's. Missing weapons, dropped weapons, voices, grenade trails, coms with your teammates, etc. It's the little details that will cumulate to give you the drop on your opponents. Just simple situational awareness helps too. If you know what the other team needs, you will know where to find them. Think from there perspective

No Scope vs Quick Scope?
I almost never No Scope. Barring mele range, I will always try to scope. Even if they are five feet away, I will still scope. What is easier to hit than a giant head, with auto aim. Even If the only reason you scope is to gain the assistance of the auto aim, it is still worth it. By scoping in "No Scope" situations you will win a majority of the time. For some people no scoping is preferable for those close range situations. My experience has been that quickscoping, even if it's just to get the auto aim to grab a bit is more consistent.

However, practicing "No Scopes" will help your aim when you do go to snipe, because you will naturally place your reticule closer to your target then you used to. Ideally, you will start to scope in close enough to your mark, that all you need to do is swipe it over them, from a close distance to get the kill.

Strafe Aiming
Just like with a BR, strafe your reticule past your mark, and fire as the magnetism grabs him. It's most effective for planar fighting, but can really be used in any situation.

Head Scanning
This is done by strafing back and forth while watching a door or hallway, with your reticule at head level. When someone steps out, the magnetism will grab them, and all you have to do is time the shot. Works like a charm, it can make your sniping seem godly on levels like Lockout.

Measured Swipe
Having a measured swipe is of utmost importance, when you are looking for consistency. If you always swipe from approximately the same distance, anywhere from 1-3 inches, whatever is comfortable for you. You will always use approximately the same timing. You will want to swipe an equal distance past your mark, this way, if you missed, it lagged, or you only managed to bring his shields down. You will be in a prime position to finish him using the same swipe to complete the kill.

*Important* If you swipe with direction of your targets movement, you will lengthen the amount of time he spends in your reticule.

Double Taps, Assists, and BR switch.

Remember that the sniping is more than just hitting the head. If you only have a body shot, take it. You may make an opportunity for a teammate to get an easy kill, with a nade or a headshot. The sniper rifle is a great assist weapon.

Not every shot is going to afford you a clean view of the enemies head. Double taps, make the enemy just as dead as shooting his face off. So weather its a boot, a backside, or an arm sticking out. Nothing surprises people more than getting sniped out of "complete" coverage.

Don't be too proud, of your sniping prowess. If you hit the body, switch to BR, to finish. At the least, you will save some snipe ammo. Let alone that it is usually more effective. Chances are if you didn't get the first shot, your second, and often your 3rd and 4th shots will miss. You hurried them and you spazed out. All that will do is waste your ammo, and get disgusted remarks from your teammates.

Circular Swiping (Advanced Snipers)
This takes a lot more finesse to perform then a normal swipe, due to the fact that your sensitivity is dramatically decreased while it is on the body of your mark. (This is from the magnetism in H2) If you perform a small circular motion, or swivel while your reticule is near your opponent. Your reticule will grab onto him. Some good example of circular swiping can be seen by watching It Was Luck.

Long Range Sniping
There's not too many situation in MLG that would require you to be really good at long range sniping. However, knowing that the mechanics of sniping are different at those ranges will help you. Swipe sniping at range is much harder. Your primary tools will be strafe aiming, and actually aiming with the right stick.(OMG!) Generally right stick the reticule as close as possible to them, and then make any little corrections with your strafe, seems to work pretty well.

Try all of these, and go through the motion until they become natural. No matter what information you read, it's not any use until you incorporate it into your style to the point that you no longer think about doing it.

More Resources

Advanced combat technique
http://nikon.bungie.org/gameplay/stratguide/combat_techniques/

Aiming and Manuevering
http://nikon.bungie.org/gameplay/stratguide/combat_techniques/aiming/

Movement techniques 2
http://nikon.bungie.org/gameplay/stratguide/combat_techniques/movement_techniques/