It's great if your team works together, but in most cases, they will split up and take the whole thing by themselves, being undefined vigilantes. At least, if you can, stick with a guy, cover his back, etc. Remember, that each weapon has its strengths and weaknesses, and pick the weapon your role defines for you. As it says in the first BCT, every soldier is a rifleman. Remember to be the best with the rifle, as other weapons don't really matter.
What you probably don't know, is that many players (pros, of course), pick their paths and don't just run around! Like this, maybe a sniper would like to pick a path that allows easy, but stealthy, movement between high vantage, covered spots. A automatic rifleman might want to pick an ambush point, where he can hide and spray a volley of bullets at whoever comes by. And a rifleman might want to to pick a path where he can keep the fighting at medium to long range.
Unlike any other FPS, AA's firefights are kept long to medium. That means you wont be able to go up to a guy, spray and pray, and then you win, and you need to treat cover like a treasure. Also, you will notice that more of the fights are stationary, and that AA limits your speed.
To be a good player, a leader, and a fighter, give out commands. Even if they don't listen, you can just go. (Note: Covering fire is important if you want a guy to reach an objective.)