Try to keep the audience away, that can be very distracting. Don't write a complete script with lots of lines to remember - they won't remember them. Just give them guidance about what to do. Beg, borrow or buy a video recorder. Hi-8 is best, but anything will do.
Lighting is incredibly important.
Use more lighting than you thought you'd need. If you can take the same scenes with more than one video camera, that would be good. I can mix and edit with what I have here. Don't hold the camera in your hand. Mount it on a tripod, and try not to touch it.