Record you entire nights set the last time you play and then pull out the recording and practice to it every night.

You'll learn to joke around with the other members as well as get used to tuning up between sons.

If there's any glaring errors on the tape.... just screw em up on purpose for a good laugh. Audiences love it when a band screws up as long as you don't look all embarrassed.
Learn your set inside out so that you can play it without even looking at your guitar.


Worst scenerio...if you actually do screw up, try to make it look like you did on purpose or at worst, emphasize it so bad that you lie down on the floor and pretend to die of embarrassement.