Rule #1: Don't believe anyone or anything you read on bbq message boards until you've had a chance to try it out for yourself first.
What started out as a "how to" phenomenon on the web has turned into an ego-fest on some of the discussion groups. As a guy that grew up in Missouri and someone that has spent the last several years reading about bbq on the web, sometimes you've got to "Show-Me" before I fully embrace and believe the advice I read about on discussion boards as THE ONLY definitive method for cooking barbecue. There's more than one way to cook prize winning barbeque. Just because Billy Joe Bob Smith cooked in two or three bbq contests 10-years ago and won a few trophies, that doesn't make him the bbq "authority".
Rule #2: Keep your cooking area neat and clean.
There's nothing less appealing about cooking food than an unclean cook or an unclean food prep area. If you want to be taken seriously as a bbq competitor, you need to keep your cooking area clean.
Rule # 3: Set a budget and stick to it.
Competitive barbecue is one sport where bigger and more expensive is not always better. There are people cooking on $250 smokers they transport to bbq contests in the back of their mini-vans and pick-up trucks who are beating the living daylights out of the $20,000 rotisserie smokers mounted on trailers and people driving $150,000 motorhomes. You don't have to keep up with the bbq Jones to compete in bbq contests.
Rule #4: Establish realistic goals and practice, practice, practice.
It's very difficult to win a bbq contest. There's 1 chance in a 1,000 that a bbq team is going to win the first bbq contest they enter. After you compete for a while, you'll begin to make subtle changes to your technique that gradually improve your results.