If you're sniping, pick $500 one... The $1000 is just a high-powered laser... One shot and dies, no zoom, but good if you're up close... and not laggin...

I usually run out with no zoom, if you suspect (no actually see) little dots behind rocks or something, then zoom (lowest possible)... Usually if someone is there, you'll see em... If no one is there, unzoom and keep running... If someone is there, make sure no one else can kill you, then zoom to around 70-80\% (Depending on range)... This is the best sniping because 1) The enemy body takes up about 1/3 height of the scope so that you can pick off his head... 2) You can still follow and keep him in your scope without adjust the zoom when he's running around...

Since you're using the $500, aim for the head if he's standing still... If he's moving and you're lagging, aim for chest since it'll be hard to hit him anyways... Fire ahead a tad (since he's runnin and you're laggin) and fire 2-3 shots... reload and try again if he's not dead yet...

When camping out in a good spot, I wouldn't move even if you kill snipers... Only move back into cover (less than 10 feet) if a vehicle is cruising by... If the vehicle starts firing, panic and run far, far away... If you are camping in a good location (not the bunkers... they suck) then no one can get you... Just point your gun at the exit where the enemy comes from and wait (after you pick off every guy aorund the tiberium field)...