From Cycle World:
The street is no place to practice advanced sportbike riding skills—that’s why you head for the track. Track days and race days both happen on the same pavement, but a track day is about improving your riding, not beating the other guy.
BIKE If your bike isn’t in top condition, you’re wasting time at the track. Pay close attention to the tires, suspension, and drivechain. Do all the work before you go off to the track. Normal maintenance aside, most tracks will require specific bike prep—taping over or removing mirrors and lights, safety wiring oil drain bolts and filters, and replacing radiator coolant with distilled water. Check with the track beforehand for further instructions.
RIDER Visiting the track as a spectator is a great idea; attending the riders’ meeting is a must. Getting your mind right (a track day isn’t a race day) is a huge step forward. If you can, arrange a lap of the track in a car with you as an observer. You can also find video “virtual laps” of some of the bigger tracks in video games and get familiar with them at home.
GEAR Most tracks require you to wear one-piece racing leathers (or a two-piece leather suit that zips together), a helmet, boots, and gloves. A back protector is a good idea, too. For short breaks you’ll probably just unzip your leathers, but on longer breaks, a pair of shorts and sandals are welcome. If you don’t own leathers, you may be able to borrow or rent a pair from a track school.