Yeah, and even if you dooooo hit that occasional bad note, unless you make a big deal about it (make a face, or look terrified at what you've done) 99 times out of 100 the audience will never know.

So just ignore it if you mess up and I guarantee that hardly anyone will notice....unless your playing a song EVERYONE is familiar with note for note. Example: Intro to Sweet Home Alabama, if you mess up there, you're probably going to get called on it, but if it's a song you wrote, just ignore it!!! :D