remember to look around. Theres a lot to look at when you're falling, don't just look straight down. And no matter how much it costs, i advise you to get the video/pictures or whatever they offer. May be expensive, but you will seriously show it to everyone you know. (plus they make some ballin' ass facebook profile pics)
oh, one last note, if you can, ask the instructor if you guys can go out backwards so you can see the plane. Doing a flip is cool and all, but if you really want to realize that you are really out there falling, you'll want to see the plane