I'm thinking about heading to an open jam at a local jazz and blues club here in town. It's kind of a fancy place with some good acts that have played there. I've never done anything like this before but I've been told that I need to go to one of these. How do these things go down? What kind of stuff do I need to know? Are there chord charts or written music or do you just wing it by ear? Give me some pointers on this.