Make reasonable efforts to make the range safe to be on (undue trip hazards, wobbly railings, low hanging branches in normal walkways, ect)
Range rules are part of a waiver/liability release form
Be firm and consistent on removing people who violate sensible range rules.
Document everything (organizing events, especially by yourself, isn't fun)
Be selective on who's invited, especially in subsequent years.
Many insurance companies consider shooting/archery events to be "too high risk", and won't offer to cover anything (found that out when I organized a local archery/arbalist event several years ago)
In the end, accept that you can be sued by anyone for anything (real or imagined) at anytime... welcome to the USA, land of the free(?). If you can find a company willing to cover it, it doesn't hurt to consider a policy with a caveat:
Insurance companies also don't care about right and wrong, or facts. They will look to get out with as little cost as possible.
Case in point: over a decade ago, guy broke into our shop for the second (or third) time, he'd already proffered $6,000-10,000 in equipment/tools. So we installed an alarm system. Guy broke in again, brother and I went to reset the alarm and check on things, long story short, guy comes at my brother with a knife, brother shoots him in the ankle. About a year later (he waited until I turned 18, my brother was still a juvenile, so he couldn't sue him), I get a notice that he's suing me for shooting him (and his dog... there was no dog)... Sheriff's office report says my brother shot him, his statement at the time, my brother and I's statements at the time said he shot him... and he was shot by a couple pieces of buckshot (I had a rifle)... didn't matter, insurance company told me that either I settle, or they weren't going to cover anything (and afterwards, I looked into it, and it's pretty common in nearly every liability insurance policy that gives insurance companies the ability to do that). There was the slightest, most improbable chance that they might have to pay the idiot, so they folded like a house of wet cardboard.
Guy got his later, got caught stealing/possessing/selling firearms while on probation less than 3 years later. I heard he got out on probation a couple years ago.
