Check the USPSA site.. they've released their 2013 Multigun rulebook.. follow it (or close approximation), use time plus scoring,,and have fun.. at the local level, divisions really don't really matter (there's no new car up for 1st place!) till someone brings a Saiga, or Tec Loaders (biggest time issue is shotgun reloads..),, semi versus pump shotgun, not a huge deal, still gotta reload 'em. big equalizer is limiting starting round count on initial load to 5 or less on shotguns..
In the new rules, there's fewer ways to abandon your firearm,, a good thing.. make sure there's no way anyone can get in front of a dumped firearm, dump tables don't work well, buckets do.. handgun abandon boxes need to be well though out so that no one gets in front of the muzzle..