Don't arrive at a gig too early. Give yourself enough time to be properly prepared but don't be sitting around with nothing to do for an hour before playing. The nervous energy can start to build in a negative way if your not occupied or even worse you may take a glass or two to kill time and with your heightened state it could be disastrous! One Guy I regularly play with is a heavy drinker before going on, he's O.K. but I don't know many that can get away with it. Also, pick your opener carefully. Don't start with tricky subtlety, belt one out! Blow off some energy early and you'll be more able to control the dynamics of your later offerings. It gets you off to a good start. As Justapicker said, pick a member or small group of the audience to start with and focus your act. Don't look at the guys playing cards or yawning it will distract you from the people who WANT to enjoy what you're doing. I used to suffer from stagefright, now I get "anticipation". It's the same thing from a different angle! Good luck!