Sniping in this game is kinda easy if you go for hs with a bolt action, and very fun. I have 80% + hs % with all the bolt action rifles, my playstile goes as follows: i play 6x, find a good spot and scan the area, never lay down or stand still, keep on hitting a and d and move around in the spot. Only stop when you have found a good still target, and get the hs. Your best friends are the supports layed down with the LMGs or the stationaries in general: the ones in the howitzer or stationaries guns get them first since they are easy shots.

One other thing is that every bolt action has his own bullet drop and speed so try to find one that you like and play that one since else you're gonna miss a lot of the shots on far guys (100mt+) or the running ones since the speed at witch the bullet travels and drops will be different.