I definitely don't fit the stereotype of "some sniper who's content to prone on a hill and pick off distant targets". I've been playing it a lot more lately and I've learned:
1) The SVD is godlike for moderately close encounters, which I face often in my style of play. Just flop into prone, zoom and click three or four times--insta-death!
2) I use the pistol a lot as well. I can be running right behind an enemy who, since my gun is silenced, will immediately start panicked bunny-hopping since he has no idea where those bullets are coming from. But by then, he's felt the MR-444 of Justice to the back.
3) Claymores can be used passively/defensively to protect your rear flank--but for my style of sniping, there's no such thing as a "rear flank." Instead I use the claymores aggressively, for those targets that see me and run after me. If I find a little crevice to hide behind, I pop a claymore out from it and wait for the satisfying boom!