1. Practice. I know this is soo cliched, but it wont kill you to play a couple of custom sniping matches on weird places, such as ivory tower, lockout, midship (Oh, God!), Beaver Creek, and any other small map.

2. Try getting more headshots.

3. Sweep sniping. With a sniper, put your reticule near your target. Fire, then quickly snap the reticule over the target's head (or body). Practice it, and try to get it smoothly and faster. Sometimes, you may feel more comfortable snapping the reticule from right to left and vice versa. It doesn't matter. This will allow you to pull off those crazy no scopes as well as some nice long range shots.

4. When sniping, use your whole body to aim. Strafe left and right to make minute changes to your aim and where you will fire. If you have your look sensitivity high, (like 8, for me), strafing is a must.

5. Change your look sensitivity from the default (which is 3? i think). Work at it gradually, until you can get it to at least five. (i prefer 8, but sometimes even thats not sensitive enough). When you get good enough, you should to be able to snipe a person right out a ghost.

6. Be patient. When being attacked by an enemy and you have a sniper, try to snipe them. Either sweep snipe them (I can't do this under pressure), or put your reticule near them and strafe until the target is in your sights.

7. Watch sniping montages. Good sniping is not so much being able to put the reticule over the opponents head fast as it is knowing when you can snipe and get a kill. I watch my friends play, and there are about 5 times per game when they are sniping and I just think, "They could have sniped them right there." They had at least half a second of that guy's head being in his reticule. I'm talking about just pulling the trigger, not sweep sniping or anything complicated.

8. DO NOT PANIC! This is very important. If you panic, you will definitely not get the kill. Just remember that its just a game.

9. Dont overdo yourself. If you cant get headshots, dont (unless you are practicing). So you waste one extra round. Its better than missing 3 times before and getting one headshot.

This is tried and true. This is all I remember doing to go from not being able to snipe a stationary target, to being able to no-scope efficiently and being able to snipe people out of a boosting ghost.

To follow up with that, here are some sniping montages...woohoo!
http://files.mythica.org/halo/halogt/halogt_18_nsk_final.mov
and
http://www.h2videos.com/Halo2Forum/SWATM6H2.wmv
I you have parents home, turn down the sound for the this one.
I recommend to right-click, save-as, because they are 30 megs and 70 megs.

i hope you realise that the majority of Montages posted on the web are completely Staged...

Not the ones I've seen...They are in-game. and not in my montage, either.

Yes...well, they are the most luckiest snipes on those montages...and it took you 2 shots to kill a guy who was AFK...(Also, if you see on those montages, they just record until something amazing happens...in Custom Games too...So it doesnt really count)

But some people can noscope like crazy. Its different.

Hi Sneamia, 2 questions
1) where URE vids???

2) how do u make vids? as all i can do is record them on a VCR. lol

All help wanted.

Blood

well, most no-scopes are luck. You get a few people who can no-scope really well. I can, not being modest, but ask my clan

so can i. ask funkmaster90...i play on the same screen as him at his house sometimes. we all have off days and stuff. my better montage will be up soon. still crossing that laziness barrier.

EDIT: Blood: you need a video capture card (just google it), mine was 20 dollars, made in china, and it STILL WORKS!!!! W00t! you capture it to your computer in mpeg format (generally). its pretty 1337 j00s (juice).