3. License. While in some cities getting a contractor's license may be more a matter of writing a check than verifying skill, check to see that your contractor lists a license required for the work being done. A license may mean that your contractor passed the required exams, or it may just mean the state knows where to find him to collect taxes. But it also means your contractor has done the paperwork and is playing by the rules.
4. Insurance. Injuries can occur on a construction site. If the location is your home and your contractor does not have the proper insurance, you may be held liable. Check with your locality for the proper amount of liability insurance, and if the contractor has employees, check to see whether he carries worker's compensation insurance.