I started playing sessions where the only people who noticed my mistakes were other musicians. Having had session etiquette drilled into me repeatedly before anybody but my instructor heard me play, I played quietly and didn't get anything worse than a little friendly ribbing. As it turns out, that was preferable. I've done a bit of busking, played some ceilis, and played in a traditional Irish trio. Chances are when you're playing your worse there is still someone in the room who wishes they could play like you. If nothing else, if it goes poorly, it will be something to look back and laugh about. It could end up being a story you tell about while tuning, or introducing a song. Generally they don't kill people for poor performances any more and haven't for several huundred years. Have fun with it. Even when the money's good, you don't go into folk music for the money, just enjoy it. Rich