First expert tip I have is for the client, when you're scoping out which company to use for your project, to inquire with several companies. Get several quotes, and then you can see in those different quotes where they itemize certain materials, certain labor hours, and that's very telling of how honest a company be- will be with you in charging you.
Also, to inquire with references from these companies. See what other clients have to say about these companies, and that as well is very telling about how this company will deliver for your project. So in doing this, in comparing and contrasting different quotes and estimates, you can see which companies are gonna be more reliable, which ones are more honest.
And don't be afraid to ask follow-up questions as well. The more communication you can get beforehand with a company is very telling of how they're gonna be responsive and communicate with you during the project itself.