If you have people request songs remember the names of the songs so if you hear them at more than one gig you can think about learning them. Even if you do not really like them, they are popular and will get people on their feet. Try to work a few of the songs into your first set. The faster you get them up, the faster the band will start feeding off their energy, making a more enjoyable night for all.
Make sure everyone is tuned up “before” you hit the stage. That way you can walk up on stage, get behind your instruments, someone counts 1 2 3 and you’re off rocking the place looking like pros.
The acoustics of the place will change when it fills up, another sound check may be a good idea if you can.
Above all remember to enjoy the gig, ignore others mistakes you’re a team. Mistakes happen.
