Very well said, Tiffany. I would add that as a contractor, you should have a written contract signed before beginning any work. This may be a standard contract or one designed by you and your attorney. Also, make very sure that you and your client understand the work to be performed. In my end of the business, this is what we call an alignment meeting. It is designed to insure everyone is on the same page, that there will be no surprises
when we are half way through the project. It also is a place to promote our company and our ability to perform
the Scope of Work as outlined in our contracts. Any thing outside of our Scope becomes a change order. But then, change orders are where a lot of money is made
As far as material is concerned, again, that should be in your contract as to what materials are acceptable and the result if they are not. And, yes, as a large company, we have a competent legal staff. But as a small independent contractor, you too can protect yourself by using standard forms and hand writing notes at the end or in the margin, so long as you and client have copies of all signed contracts.
A standard form could be as simple as the statement used by your local car dealer's shop authorizing the work to be done.