Even if we gave you tips without any tourney experience, chances are your not going to be able to beat them. Assuming they have some tourney experience and practice together.
But I'll give some basic tips.. (there are threads on pbnation somewhere that go into detail of strategies and how to play positions and bunkers, what to do off the break ext.)
Most important, walk the field and try to find the good bunkers and the good angels. Have your team mates go into the other bunkers on the other side of the field to see if your open to them from that position.
Second, during the game keep talking to your team mates. You should never have to guesses where the other teams players are on the field and how many are left.
Third, keep the guns up and shooting.
Forth, keep moving up the field. If the other team isn't shooting at you and you cant see anyone to shoot at, move up.
These are all very basic but pretty important. I suggests hunting down the strategies/tactics threads I mentioned and read as many of those as you can. This is your first tourney, ignore the smack talk, go, have fun and learn.