Make sure your brakes are up to the task. Get some good pads, SS brake lines, make sure your fluid is good. Get some good tires. Wheels can come later. Make sure you have a helmet, they wont let you drive without one. Check with the tracks/events you wanna race at and make sure that the car will pass their tech inspections.

Maybe try posting this in the Auto-X/Road Racing Forum. they can steer you better than most people in here.