Re: First Gig
Don't screw up!
Practice, decide what material you want to play before the gig and make set lists/song lists. Get their early, tune up and get everything situated. In other words, be prepared. As long as you're prepared, you have nothing to worry about.
And probably the next most important piece of advice I can give you, is to have fun! As long as your audience can see that you're having a good time, they will love you even if you suck!