12. If you accompany yourself on an instrument that needs to be tuned, tune it before your turn comes around, so that your performance can begin straight away rather than being preceded by five minutes of ying-yanging and embarrassed muttering such as, "New strings" or "It was in tune when I bought it in 1952".

12a. If you're tone-deaf and unable to tune your instrument by ear, make sure to bring a fully-operational electronic tuner to the singaround, and be fully conversant with its operation. Use it to conform to (12) above.

12b. To avoid time-wasting when you need a capo and have to resort to borrowing one, and then can't decide where on the neck to place it, bring your own f***ing capo and know in advance which fret it needs to be placed on!