Originally Posted by draeh

Tactically, keep moving. Never stay in one place for long. Even if all your doing is turning every so often to check your surroundings. Work on your situational awareness.

Aye, I agree with this. About 80-95% of my kills could just as well have been made with a Baur, Voss, Krylov, Scar, Lambert, Shuko, Ganz, Bianchi, or the Engineer LMGs: it's all about getting into position. The twitch reflex and accuracy play such a small part in killing, it is ridiculous.
And there's no way to gain the placement advantage without experience. It's not something you can be taught.

For practical advice: check your six often. Do not go prone in fight unless you have a very specific reason to do so. If you are a sniper, do not make a hen's nest and snipe from there, no matter how static the fight lines may be: always stay on the move. From experience, 50-80% of my knifes are snipers and infantry prone and zoomed in far away. And same goes for my sniper kills.
Best way to avoid this is to get behind cover such that you are covered completely when you crouch, and partially when you are standing. Then, simply pop out, scan the area quickly, and pop back down. Second run, pop back up zoom in on a target, pop back down. Third run, pop up, headshot or body shot pop down. Fourth run, clean up.
This kind of bouncing around from behind cover ticks off snipers trying to get you -- you are not an easy kill so they give up, and it makes you less static and lethargic so that you see and hear infantry in your immediate vicinity and at your sniper's range.