Three things to do lots of:
Shout, Shoot lots, and last, but definatley not least, have fun.
One thing which migt be worthwhile, is setting yourselves small achievable targets - for example, out in Toulouse, Pompey Uni's aim was to not be maxed by anyone (which we almost managed but for the Rushers) and to not finish bottom - anything else (such as the odd game win) is a major bonus.
As you gain more experience of playing Sup'Air tourneys. you can add things in, like the front players aim to do at least one muggingd per tourney, things like that, or each back player aims to be last man standing.
I'm certainly no expert in the field, and if none of the above seem sensible, just remember, keep it chilled, give politics the finger (that's paintbal politics, not Mr Blair
), remember that you're putting a decent size investment into paintball, and enjoy yourself.