I think we could all benefit from some standard practices due to the PS3's sub-par communication interface and what seems like less than 50% of players online having mics.
1st: Determine who will be the Cake Feeders - press start to check the roster, if you're one of the last 2 non-a.i. players then you take on the job of making sure the prisoner is full of cake and playing defense.
2nd: Determine who will work on upgrades and repairs - check the roster and whoever are the next 2 non-a.i. players, you take on the job of repairs and upgrades as well as defense when called for.
3rd: Everybody else on offense - anyone else left goes on the offensive. Hell, maybe even make offensive strikes with more people than just yourself (thank God there aren't any boats or tanks to take off in.)
I understand that the roster changes throughout the game based on points earned. So when I say check the roster to determine your role, just go with it from the beginning of the game.
Of course all this would only work with more than 2 non-a.i. players in a game which seems like a hell of a feat right now as far as the online portion goes.
I have found communication to be terrible on the PS3, but I've only played a few online games using the PS3 service. I know that part of this is due to the lack of players with mics, but even my mic doesn't seem to work sometimes.