Going on from the Rate of Fire comments, quite a lot of sites have a 'no full auto' rule, also with it being CQB it'd be worth thinking about FPS limits and a chrono policy too.
Liking the idea of easily moveable walls to keep it fresh as well as upping the realism with a few extra props etc.
Also, go and have a chat with the competition, they may or may not be receptive but if you're all within a sensible distance of each other then you'll all be after the same players and their cash. It's all business at the end of the day and a bit of competition is healthy, but it's definitely worth making it 'friendly' as you never know who you'll need a favour from in the future. May be worth looking at when their midweek evening sessions are (if they have one) and doing yours on a different day?
Having a shop selling incidentals and stuff that people have a tendency to forget to pack will provide a nice bit of additional income, you could come to an agreement with a local store or do your own thing. Selling snacks and drinks is always going to be popular and you'll get brownie points from the local business community if you can get local lunch van to pop by - just make sure you agree times and also that the session is over in good time for everyone to get their kit stowed and be ready when the van arrives.
I've always wondered about the on-site store carrying a demo fleet and doing RIF rentals in a try-before-you-buy capacity (sort of), eg rent a RIF for £20 for the day and if you buy one you get the money back. No idea if that'd actually work.
Carry enough spares to ensure you can keep your rentals happy, no-one wants a game day ending with a broken gun. Also rentals are future regulars, you need to make sure they have a good day as you've the least goodwill built up with them, flip-side of that is don't forget the regulars as they are a reliable income stream - it doesn't take much to keep people happy.
If you've a local technician doing gun servicing on site for your rentals then why not re-sell that service on? or maybe set up as a range once in a while for people to come and test that new spring to ensure they're not running hot or set up their new sights or hop-up in advance of a game day.
Final point, make sure the parking's covered. You'll lose customers and sour relationships with your neighbours in no time if parking's a hassle.