So, as an investor/landlord and real estate broker and owner of a property management company I probably talk to 2 or 3 distressed landlords a week.  I have noticed one key thing with all of them.  This holds true for the owner of one property who is new or the owner of numerous properties that has been managing them for years.  Here it is:

The key is they either don't have solid systems in place or they don't enforce their rules/use the system.  The owners for whatever reason stop running their business like a business.  They don't enforce late payment penalties, they chase the tenants around for money and the list goes on.  As the manager of my own properties and properties for others I can tell you without a shadow of a doubt you have to make the tenants live by YOUR rules.  When we interview prospective tenants we spell it out for them right then.  Here is our payment system, here is our maintenance request system, here is the late fees, here is what happens if you leave broken down cars in the yard or have a dog you didn't disclose to us. 

 I have on occasion broken this rule and taken tenants from the previous landlord (mistake) and I could never get them to live by my system and I always ended up terminating the lease.  So please hear me when I tell you come up with systems to make your life easy and it gives your tenants boundaries of what is and is not acceptable.

Good Luck

Gavin