Most important thing is situational awareness. Try remain in cover as much as possible, due to the map layout you will get attacked from everywhere so try and reduce those angles as much as possible.
Be an engineer or medic first, this way you can heal, revive, drop ammo, repair whilst you get a feel for the game and your certs (currency) will fly in. Concentrate first on infantry, ignore vehicles until you're confident enough on foot.
On my way out now but click this too Gary:
http://forums.overclockers.co.uk/showpost.php?p=28220464&postcount=24
I probably won't be on tonight but Stretch and Lee are quite good as well now, they'll probably add some bits.
Just remember that it will be quite daunting at first. It's known as a noob unfriendly game but once you start making sense of it all there's a brilliant game underneath.
Oh one more thing, we're New Conglomerate on..... dunno, not Ceres, the other one.
And another one more thing, don't buy guns. The default New Conglomerate guns are some of the best in the game.