If belts are all you want to do, the "Belts Galore" book by Al Stohlman should get you going with what's needed to create them. If you want to expand on that, the book by Valarie Michael "The Leatherworking Handbook", has just about everything a shop will need to produce belts, handbags, wallets, and the like,
Saddlemaker....different story.
Since you're a shooter, you might consider making holsters as well.