DON'T DRINK BEFORE A GIG! It will screw up your voice and your finger co-ordination and maybe prevent you from noticing; and you'll suffer just as much terror if you have to go on without a drink. Cold turkey is the only sure-fire way to handle it. Your need to perform outweighs your stage fright, and the stage fright will fade you become accustomed to performing. Everyone gets it, especially at a strange venue, but we (i.e. you and us) can handle it--just believe!

Steve

P.S. And you can always have that drink later.