This also brings to mind another question about pets.

Utility bills, smoking in the unit, pets, parking, who and how to contact in an emergency, what constitutes an emergency, etc.

Pets?

Think of all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

Also, I allow pets but some folks want to bring in the zoo.  

I would imagine that this could be taken similarly to a no pets clause with a service animal.

Also, I would probably not rent to tenants with pets or young children, since the potential damage/cleaning could make it more of a headache than you get paid for.  

Aside from all the house rules about usage, bills, pets, family, maintenance, etc., I'm not sure the best way to structure a potential deal. 

What type of Pets are legal rental pets?

They are rented by one or two people, usually with no kids and no pets, and they work all day so there should be less wear and tear.