Set up several load outs that will allow you to switch between your favorite syles. I have three loadouts I use, one med, one repair, and one commando (commando has gas gernades, anti-personal mines and gernades. I use it to get in and do a lot of damage then switch back to med so I can support the squad as they move forward).
Learn the maps. There is a lot of stuff in the maps in this build and a lot of places to hide and move forward or pick off.
The shiny boxes aren't the only things that will refill your equipment and health. You can also get into a bunker and it will do the same.
Smoke gernades are highly effective if you are trying to get your squad to an objective. 1 person on your squad should always have a set.
Gas gernades are great, they just have to drop after u set a charge to keep the enemy from defusing or keep them out of the weak spots that will allow them to flank you.
If you haven't noticed going prone in this game is really effective, espically during a firefight.
Always protect the AA, if you lose the AA and can't get it back quickly. FALL BACK and ditch the bunkers they are all ready behind you and going for the objective.
Continue to post what works for you here...everybody plays differently it is good to know what works for us since we will be playing together.