Insurance and safety certification are "must have" items, before you EVER charge a single admission... APL is the only operation that offers guidelines / requirements for safety certification. There are 2-3 semi-major carriers that will write policies for a paintball field. Easy to find.

Wholesale accounts and suppliers are also easy to find. There are several that would love your business, but pick the one that fits YOUR needs, not theirs. All you need to set up a wholesale account is a business license and a retail license. You would be amazed at all of the "bait and tackle" shops that have both of the requirements AND are now PB retailers. They don't know WTF they are selling, but they do like to sell it...

PS: An industry driven by paintball players, for paintball players, is better than an industry driven by non-paintball players for dollars.