One thing I would stress to folks who've never had a booth before is to prepare for wind. Even a breeze, if it's blowing in the right direction, can cause problems. I've had a corner of the tablecloth blow up over my jewelry repeatedly, all day, which sounds trivial but can become a real pain. And of course, panels are famous for blowing over. So when you set up your booth to test it before the show (OUTDOORS, if possible), consider anything and everything that might be affected by wind, and plan how to mitigate the problem.
Along the same line, be prepared for uneven ground. It's always good to have a box of stabilizing stuff: pieces of wood, bungee cords, regular cord, clips, etc. Even weights or sandbags can come in handy, if you have room for them. -Rikki