A written very detailed contract. Keep in mind that when the deal is made, it is essentially their land (as it pertains to hunting) for the period in question. You cant come in later and cry foul just because they are engaged in legal activity that you suddenly decide that you dont want them to do. Also, best to keep in mind the potential costs to yourself and others. If the people who lease it decide that they want to try to manage it for large numbers of deer but only want to take a few bucks, then there is the dangr of ending up with an overpopulation of does and young bucks whose damage of crops, etc. in the area may end up costing more than what you make on the lease.