My procedure is normally give the golf a damn good clean the night before the show along with a wax. Jack car up, clean under the arches, apply plastic trim gel to arches and then rub down so its no longer sticky, clean windows inside and out, clean the wheels off the car, inside of wheel too, wax wheels, clean brake calipers, clean inside exhaust, clean engine bay area (if your gonna show it off). Then when i get to the show i have a portable hozelock pressure washer which i soak the golf in, wipe her down with a chammy, clean wheels, give her a good detailing, then i either wax or quik detailer her. What i also find usefull is once you have finished, drive the car back and forth and brake a few times to clear that rusty look off your brake discs.