What do I need to know about leasing?

So I am thinking of leasing my horse. If I can find him a good rider/caretaker. Also a possibility of selling him to the right person, but I would start with a lease.

So my question is, to those who have experience leasing, what should I be sure to do? I know I need everything in writing, detailed out, but what should that encompass? Any advice or suggestions on finding a leaser and getting the process going?

Thanks in advance!