Targeting Goggles are a great tool for getting your bearings. Makes enemies much easier to track when you've tagged them, and even if you don't kill them yourself, you'll get lots of assist points from teammates. It's really useful to study what the other team is doing when a match begins and plan accordingly, oftentimes I'll start the match with these to see what types of builds the other team is rolling with, then respawn as whatever class is best equipped to punish them. EG: If a bunch of guys are gliding around, break out a class with Airspace Deniers; If there a bunch of speedy/nimble guys zipping around on rollerskates, break out one with Bear Traps or Trap-in-the-Box.
Weapon-wise, Gatekeeper is definitely the best spray-and-pray option, comes up quick, nice fire rate, nice damage, decent clip size.
I always like to have a Deep Freezer or Bear Stalker as my second, they're sniper weapons but there's no penalty for firing from the hip like the sniper rifles themselves (in fact, the little HUD dot in the middle of the screen feels more precise to use for aiming than actually looking down the sights). These weapons are especially great when used in conjunction with the Targeting Goggles; Real easy to stalk someone and nail 'em with a fully charged shot as soon as they round a corner.
Support items, I'd go with Bear Traps or Airspace Deniers. Bear Traps laid around objective and high-traffic areas will snare people constantly, and Airspace Deniers are great for those matches where you run into a bunch of people that just hover around and dive-bomb constantly.
Fun Facts are important, too. I go with Wallflower (not detectable by enemy sniffers/targeting goggles) and Hard Target (no extra damage from headshots), those are far and away the most useful ones IMO.
