Best advice I can give you as an organizer is Get Help. Lot's of it. You'll be amazed at all the details there are to take care of, and you'll need plenty of willing volunteers to make things run smoothly.
Start with the info for organizers from the KCBS site, then initiate communications with your prospective Rep as early as possible. An experienced Rep has seen many contests, both good and bad, and should be willing to assist you with getting a new contest off the ground.