Playing live for the first time.

In about a week and a half I'll be playing live with my band for the first time.  We're a folky acousticy kind of band and we'll be playing at a local pub.  We've got all the live musical gear we need, monitors, PA, etc, but I'm pretty nervous.  I keep thinking I'm going to mess up and ruin it for everyone else. Can any performers out there give me any tips on how to avoid nerves?