Use buildzoom: they do the work to verify a contractor and find the best fit for you based on location and project type. Also, call the contractors listed and ask them for references from past customers and talk to them. It requires some research on the homeowner’s part, but if you look at reviews from different sources, that is the best way to find your answers.
The best way to find a Contractor that will do a good job first and last thing you do is go to buildzoom.com they do back round checks on Contractors AND make sure they hold the license and insurance so really you cant go wrong other then that you would take a chance with a person thats not fit for the job buildzoom makes sure they send the right person to your door step your welcome.
Word of mouth is always the best reference.
The second thing to do would be to call your local Dept. of Labor & Industries or go on their website and make sure the contractor is licensed, bonded and insured. You can also check their history on there and make sure there are no current or past complaints on their insurance or bond.
Last, run their name on the internet and read customer reviews. Buildzoom is a GREAT source as well as google. Good Luck 
Most states have registration numbers for home improvement contractors that by law, should be listed on all consumer related contractors, quotes business cards panphlets etc. This number can be searched on state websites for any lawsuit involved with the contractors that you should be avoiding. Buildzoom, google and Angie’s List are our favorite choices for internet reviews. We are new here, but like the thoroughness BuildZoom uses.
Other than BuildZoom, your best bet would be review sites like BBB, Google Reviews, Angie’s List, Yelp, Yellow Pages, Houzz and more. Look for companies that have a good rating and be sure to read all the reviews and comments to determine whether the company is a good fit for you. It’s always a good idea to research a team that will be coming into your home, business, or place of work to ensure your safety and the integrity of the project.
Let me know if you have follow up questions.
Emily W
Decorative Concrete of NY
[email protected]