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.

Do they have unauthorized occupants, pets, smoking, etc. 

I couldn't ask about pets, smoking, how long they planned on staying, etc.The other nice feature is the applicant can upload supporting documents like a driver's license and pay stubs.

I have a rule against pets but 2 of my longer term tenants have cats (without asking permission). 

Easy to adjust rent payments or add in fees for pets, damage, etc.

I have four accounts over $10,000 and most of that damage is from pets or because an owner refused to let me take action early, usually because of some bleeding heart story.Find a professional, at least until you are more stable and prepared to take on management yourself.Remember: cheaper doesn't mean you'll make more money.Start by going to www.narpm.org to search their directory of managers.

He asked that I have it professionally cleaned and treated for pet urine upon moving out and I did, but he came in to inspect with a black light and saw spots.

No one will ever care about vetting that tenant as much as you and its a great learning experience.  2) Keys should never be handed over until you have copies of all utility transfers and verified, renters insurance, rent for the 1st period due, pet insurance/vaccinations or any other its required in your lease. 

For example, I mention that every adult must pay a $30 application fee and pass my credit/criminal background, they must make a combined income of 3x the rent, and whether or not the property accepts pets.

Some I can think of off the top of my head:  Buy-out agreement, unauthorized roommates, pet addendum, renters insurance requirement, if house is located in HOA then tenant is responsible for any fines, etc...