I'm going to be sitting in with my cousin's band the end of this month on lead guitar and backing vocals (for the most part). I have a copy of the set list but will not be able to practice with them until the day before the gig. They do a mix of covers and a few originals, some of which I'm familiar with others not so much. I'm flying into Costa Rica for the show, so I plan to bring my own picks and fingers and not much else. If I am lucky I will be able to borrow a guitar and an amp. Last time I sat in with them I used one of their guitars when they weren't playing it (on mandolin). I wasn't able to do any "tweaking" to the sound other than adjusting the guitar's pots. Anyway, I'm just looking for advice on using strange gear, and playing new material without much practice time. Fortunately I'm very familiar with a few of the songs, but it's three sets of 13 songs each. They tend to do a good bit of arranging (and last minute key changes) so I am not going to be attempting any note for note versions, not that I really even could. I'm planning to focus my practice on getting the "feel" of the new songs, and try to "approximate" any signature riffs, but I will be improvising "on the spot" for the most part with all of these new songs. Any tips to help me be as prepared as possible? Mistakes you've made that I can learn from and avoid? Thanks in advance, and BTW, everyone is invited to the show!