Payment is a pet peeve of mine whether it's a renter or owner. If you are in this business for several years you are going to get stiffed a few times. Not paying in a timely fashion is the quickest way to get me to drop a customer.
The key is to wade through a bunch of customers until you develop a group that has proved they can be trusted to pay when billed. That's only possible if you're a small operation and not a LCO that's constantly looking to increase the number of accounts. If you're always adding new customers you're always going to have newer people that aren't proven payers.
I have a couple accounts that have to get a phone call about what they owe from time to time. Everybody else pays like the Bank of England and has been doing so for a long time.