I agree with Shafted and the other commenters. Survey the field and "spot" enemies as much as you can before proceeding. You really have to look to see where anyone is in this game! I started working through the Engineer kit, since it's a decent balance between a rifle that does damage and anti-tank weapons. Medic will get you leveling up FAST with revives and dropping health packs for your teammates, and once you get a scope on the M60, you have your "beast" weapon (you can take out snipers from 400 yards with it :) I found Assault kinda useless strategically, but it's still fun, and am just starting to slog my way though the Recon kit. I'd also recommend looking to see what kits your squad and team have equipped, and then pick something that is in the minority so you can get some balance going--you're not going to win if everyone on your team is an Engineer or they're all Medics! Finally, once you get the Magnum Ammo perk, always keep it equipped--it's the same as Stopping Power in MW2.