The best advice I can give that hasn't already been given is don't sweat the figure 8 box! It's only a small part of the riding test but people freak out about it. They take points off for going outside the box, and for putting your foot down, so whatever you do, don't do both! I would say concentrate on having good form through the turns, and if you happen to go outside the line, oh well. The only things that are big no-nos, if I remember correctly, is when you do the 'emergency stop' make sure you get down to first gear, and of course, don't dump the bike!
Big +1 to everyone saying just have fun. If you have reasonable coordination and awareness, you will do well. The bikes are light, the speeds are low, and you practice the hell out of everything you will be tested on. I honestly kind of miss weaving through cones and riding over 2x4s.
