Preparing for a gig

This topic interests me because, since setting my goal of just putting myself out there at sessions in 2009 I have had some bookings (paid and unpaid) to play support slots at folk clubs. So I have been trying to sort out a general strategy for preparation for these. The obvious ingredients are:1) Have an idea of the likely audience/purpose so that you can choose a suitable repertoire of materials2)Practice, practice, practice to make sure you know them well3) A range of strategies to manage performance nerves and harness them as a positive energy4) Go prepared for the unexpected (e.g. spare strings, set list plus back up list - I have had to do 40 mins instead of 20 mins when another musician was ill!)So what other good advice can we put together from our collective wisdom?