yah get really drunk to the point you can't remember your mistakes
I got buzzed prior to my set last Tuesday and midset thought I was going to piss my pants. Smoke weed, bring some water on stage with you.
Just act like what you're playing is the greatest thing you've ever heard and react to it. Don't be discouraged if you: fuck up, stare out to an emotionless crowd, see people walk out. Your discouragement will transcend into your performance and people will sense it. What you do on stage is huge and musicians tend to take it for granted because they think their songs are so rad that they can get away with standing there like statue.