You Don't Ask For References.

This is probably the easiest way you can avoid any problems with a contractor. ALL good reputable contractors will eagerly give you references.

Ask your contractor to give you at least three names of people who they have done business with. And also ask them how long they have worked with this customer.

Also ask them what type of job they did for those references. Try and get the names of customers who had similar things done that you need done.

This is the easiest way you can pick the right contractor for YOU!