Ditto what Pete said. Practice. When you recognize that professional touring musicians still warm up for an hour or two before going out performing the same songs that they've played 10,000 times (literally, not figuratively), I think you can let yourself off the hook for needing some work after just having been at it for a little while.
If it comes from the heart and you add a few beers... it'll be awesome! - Mekidsmom
When in doubt ... hats. - B.G. Dude