I'll just list what works for me, feel free to tweek these:
1. Assassin and Marksman for a more support sniper role. Assassin keeps your name from showing up, and Marksman lets you aquire targets from longer range.
2. If you're gonna be using an ACOG, then Assassin and Quickdraw are your best two choices for perk 2. Whichever one you don't equip, make it your first Specialist bonus. Stalker Pro is also your top perk 3 choice. You give up some target finding at range, but since ACOG kills your range you'll want to be able to strafe faster.
I'm far from the best sniper, but these have helped me. Happy hunting.