My first performance was at a recital when I was in seventh grade. There was like 100 parents, and being parents and all they were nice. I played and sang "Teach Your Children", and it was good times. I enjoyed watching all of the older kids who played guitar play. I watched in awe, but now I can play pretty much as well as any of the boys I watched in awe.
Picture everyone wearing their underwear! The classic advice. I never get that nervous, because I've been in drama so long... Deep breaths, and don't throw up. :)