As others have said, preparation is the #1 key. If you are comfortable with the material, know your parts, have good relationships with the other band members, and are also comfortable with your gear - things usually go fine at a gig. Included in your prep should be things like: 1) Making sure you have a backup guitar and amp, 2) knowing what you will do if you break a string or something happens to your axe or amp during a song, 3) etc. Take care of and address as many potential "unknowns" as possible before you go onstage. Mitigate your risk. As Pete Thorn said in his article, make sure you and the band practice as if you were at the gig. Use the same effects, instruments, etc. By the time you get up on stage, if everything is well rehearsed, the gig should be like practice - except you will be riding the wave of energy from the crowd. If there are other variables getting in the way - like stress from work - do what you would normally do to relieve those pressures.