OK,
I too felt a bit useless during some of the clan matches last night. Got a respectable number of kills, but as was pointed out, that doesn't necessarily help your team win.
Some aspects of teamwork are easier than others. If you see your guy running with the enemy's flag, it's pretty easy to know to run in and cover them. Pointing out where you saw an enemy is easy too. But a couple of people were yelling for us to do stuff which I either didn't understand, or I was nowhere near the area. Then they gave us all shit after the game for not working as a team.
One quick tip I think I noticed might help. If you are driving the warthog waiting for your guys to come out with the flag, do not ever stop driving around. If you stop, you'll get rocketed or grenaded for sure. Better to not engage at all if you can run.
Also, sorry for all of you I accidentally shot at! The good news is that I usually stop right away.

The bad news is that I did betray one of you, but you had jumped in front of my blazing guns with no shields left, so it wasn't even a twitchy trigger finger issue.
Anyway, lots of fun. Hopefully I'll get better. :b
How did the AVS challenge go?
Mister Creosote.