Hmmm...
Won't give away my best secrets but I'll chime in a bit.
The Highground
The high ground is always the best. Especially that closest to the base. The higher you are and the closer you are the more of the courtyard you will be able to see. Also, when you are looking over a steep incline you are harder to hit by other snipers below.
Shoot-&-Move
The only time you move is if you are taking enemy fire. Shooting and moving causes you to lose sight of your target. This means he got away and now knows there is a sniper out there. You will die because of this. More often then not, the snipers that say you need to shoot and move are the ones who shoot alot and miss alot. If you can't shoot to kill, then don't shoot. The only thing you are doing is drawing unnecessary attention to yourself.
I will say that I do move around in a couple of situations. When there are vehicles/maxes present, and when I am engaged in a hunt. There are a few good snipers out there I have a never ending duel with. We never kill eachother only wound. This is because we are so focused on the hunt for one another we can't afford to be in the same place twice. We fire on eachother, but once we are spotted we have to move.
Fog
Fog is actually your friend. There is a sweet spot that once you find it, you will rack up the kills. The position you are looking for is when the enemies become merely shadows on the horizon. This means you are also a shadow, and when next a tree or rock you are invisible. Watch for the shadows to move, and watch for the tracers. Estimate where the tracers are coming from and fire. More often then not, you will score a hit.
Leading
Leading is done by feel. Every battle is different and every zone is different. Prepare to miss the first couple of shots when shooting at moving targets in a new zone or a new battle. Varying amounts of packet loss and lag will require you to adjust the feel for how much you will have to lead your target. This will become very natural will time.
Prediction
Predict where your target is going to go. If he is crouched outside of a tower and there is a door behind him, that is where he is going to go after your first shot. Fire and reload, during the reload take aim at the door. By the time he reaches the door you will be ready to fire agian...kill him.
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