Sniper, no sniping! 

That was a Dora the Explorer reference for all you Dora fanboys! In this case though, we want the sniper sniping (totally a word). And the best custom LEGO gun to snipe with is the Suppressed Sniper. With a built in scope and silencer you can get your sniping done accurately and discreetly. Just don't wear white like this weirdo in the picture. Amateur!

Create your own sniper minifigure with a Do Rag and Bandana. It's a good idea to have a back-up gun like the Special Forces SMG. And if all else fails, keep some Dynamite handy to blow up any counter-attack by the enemy.