Getting started
When you're asked to sit in with a band or you're playing in a jam session where you can play more than one song, choose to play your least demanding song first. It takes most people one song to warm up. Most players, myself included, will tend to be a little anxious and get a little dry mouth when first jumping up to play. Choosing a less challenging song to start with helps to get your juices flowing, gives you a chance to drink water somewhere within the song, helps you to become comfortable with the setting you're playing in and get used to the way your equipment sounds. After this first song you should be ready to play your kick-butt instrument.