You need a few things:
1. Model release form/contract.
2. Professional hahahahahar, because your literary skills won't make the team.
3. Perhaps an attorney who will be present when both you and the model sign the releae form/contract.
It's probably good to have a third party present to witness the sober signing of any contract, especially when there is money involved. The professional third party/attorney will save your ass later if you're involved in a contract dispute that's in your favor.
If you need a professional hahahahahar to draft/edit any contracts/forms you come across, contact me via
http://www.twelvefifteen.com and I'll refer one to you.