I'd have to say Materials is one of the biggest factors. So many people these days use regular vinyl that just doesn't hold up to the demands of Motocross. Good quality vinyl and laminate is a must. Then next would be the templates, without them it's a shot in the dark. So many bikes out there that each make and model has different plastics. You can either buy the templates pre-made or make them yourself. Then designing, it's completely different in my opinion than car wraps.
Just like Flame said, be prepared to be dedicated to it, no half a**ing it.
templates are another huge obstacle if you're looking for pre-cut graphics. We do wraps, patterns only where the customer installs the product theirself...
There are so many different types of body work out there(4-7 brands per year per model motorcycle), that it's difficult to produce pre-cut kits for the racing industry, where they;re most valuable (crash rate/repair is higher).