Purchase surety bonds. Surety bonds essentially act as a kind of agreement between the contractor and the person hiring them that the job will be performed to standard. You can obtain these through your current insurer as a separate form of financial protection. As a contractor, many states require you to be bonded before you can begin working legally.
The other difficult part is getting a painting contractor to show up. While this generalization does not apply to every painter, you can rarely get a paint contractor to show up to look at the house and to later produce a written estimate. It's hardly the fault of the painting contractors; it is a combination of the contractors being smaller operations along with a high demand for their work. House Painting Westminster