Hmm well if you ask me i would have to say
1. If you can get the headshot TAKE IT!!
2. If you think you just saw somthing move then when in doubt EMPTY THE MAGAZINE !!!!
3. When a player comes translocating at you ....do the same back then stop crouch and shoot him while he is still transing looking like a fool 

AND MOST IMPORTANT 

4. WHEN PLAYER {dFb}GODZILLA IS SEEN...........TRANSLOCATED AWAY!!!! 

lol well those are majers tips to sniping welcome to the forums!!