Interesting, the various comments about song-sheets. I can see their social function in a church,but at any sort of music/song session that I go to, I'd think they'd be a disaster. Yes, sure if Joe Bloggs has brought along the words to his new song in case his memory needs jogging; but giving them out to everybody? No thanks.
   Songs v tunes and jamming along: it's a rare session where tunes and songs happily co-exist. That's where I'm happiest, but it's difficult to keep that working, because good sessions inevitably attract new people, and some of these will always be people who arent temperamentally able to fit into an "anything goes" environment, and they will start bending proceedings to their tastes. Best thing then is to move along and start a new one, but this isnt easy(or desirable) if the session was something you started in your local.
   Jamming along: Marje's comments are very true, it seems to me. If people are doing songs that go G C D7 G, as is probably more likely in an American session, the process probably works, and can readily accommodate extra guitars, fiddles, mandolines etc. This is by no means the case if you're somewhere in england where people are trying out their latest Martin Carthy/Nic Jones licks. Best let them get on with it, unless you're a very fluent sympathetic musician with a brilliant ear...in which case you'll probably let them get on with it anyway!
   And a final point: if the technical quality of a person's performance is relevant to whether they should be performing or not, I doubt if it's the kind of session I'd want to go to. I love it when Uncle Bob always sings "I'll take you home again, Kathleen", even though he's crap.