I instructed out of a flying club many moons ago.

Ask if they expect a cut from your fees. Mine didn't, so that $20 per hour went into my pocket. It's a better deal than a student paying $50 and the CFI getting $10. Ask if there is an unspoken minimum fee for your services and if you are free to set your own prices. Verify that your covered by the flying clubs insurance or are you just like a renter. If the later, and you have any assets, look into CFI insurance (it's expensive).

Ask how CFI referrals work. My club pointed to a line of business cards on a shelf. It helped if you lived on the couch in the office.

Ask if they expect you to "help out" around the office. If it helps get flight time or student referrals, great. If not, it can be a bad deal.

I believe that I made far more money than my friends flying out of an FBO. Remember that you'll have to market yourself. Check out the threads on how to do that. Expect some dirty looks from the FBO crowd. I have found that most FBO's are at odds with a flying club (assuming that the flying club offers instruction).