The bigger your business becomes and the longer you stay in it, the law of averages dictates you’re going to run into a dishonest or crazy customer along the way.
I would like to start by saying that none of the following information is legal advice. I’m not a lawyer and my suggestions are based on my 40 years of dealing with contractors. All state laws are different, and you should consult a local attorney. Legal advice about “what-if” situations is always cheaper than “oh no” situations. In other words, know the law and obtain legal advice regarding contracts, documentation, lien laws, etc. Legal advice to stay out of trouble is always better than throwing good money after bad money once there’s a problem.