Bear in mind that how well one performs a tune is far more important than how many tunes one can plow his way through. It is better to play a few tunes well, even using preplanned variations, than to play tune after tune in an erratic or sloppy manner. Practice and memorize tunes. Always try to play in a steady rhythm and never play faster than is comfortable. The worst failing of the overeager session player is to hold back the session by playing in fits and starts, interfering with the natural momentum of practiced players by constantly interjecting half-played or faltering melodies. In this way, one soon becomes a nuisance to the majority who know better.
For the beginner, newcomer or non-player, it is only proper to ask permission to do such things as tape, take photographs, or shoot videos at a session. The regular players will usually grant such permission, but the newcomer should not take it for granted.
Even asking if a seat is taken before sitting is the socially correct thing to do. Quite often, the best seats are reserved for respected musicians who have not shown up yet. These players might not even show up, but being refused a seat is not intended as a snub; on the other hand, earning a seat closer to the center of action is a fair goal for the newcomer to a session, though this may take some time, focus, and energy.
Keep focused on the music and share it with everybody. Those whom you touch with the spirit of the music will be inspired and entertained. You carry the tradition.
by Tom Hanway
excerpted from The Complete Book of Irish and Celtic 5-string Banjo