Try and take your mind off of it, listen to music, hang/talk to friends/family, relax and know that NOONE wants you to mess up. There is no reason not to go out there and perform your best. Have fun (:
Remember people are there to see you! YOU! Do get nervous you made it on stage you are great. Do some yoga before the concert and just think about what u are singing not about the people out there. Hope you do great!
This might sound odd but when i used to act and stuff i would spend like the last 10 min of prep time and get fired up and do crazy stuff like pushups and jump up an down...idk iv been performing for a little while so it doesn't bother me
Pretended every one is in your world. Play and laughed to yourself. Look past people and think of only what your doing. Think of good times and prep yourself up to being hyped but not over hyped. Think to yourself I am awesome :)