If you're a smaller business or a freelancer, you don't really have a lot of help in this case. Make sure they pay often and frequently as you go and if they don't pay, stop doing work. Unless the amounts are a lot of money, getting the legal machinery going is very difficult and expensive so if you're just doing a job for a few thousand dollars, the legal system is probably not going to leave you net positive. IME.
If you're a smaller business or a freelancer, you don't really have a lot of help in this case. Make sure they pay often and frequently as you go and if they don't pay, stop doing work. Unless the amounts are a lot of money, getting the legal machinery going is very difficult and expensive so if you're just doing a job for a few thousand dollars, the legal system is probably not going to leave you net positive. IME.