What most naturally follows?

How to collect money owed for work done
Research your customer's credit before doing business with them.
When you do a large job for someone, consider running a credit check first. It is not that hard to get set up to retrieve credit reports.
You may find out that the customer has a habit of not paying their debts, so it's worth it to check before entering into a deal with them. You can also use the risk of not being paid as a justification for raising your fee.