Lisa offers excellent advice and her firm does good work.
Consumers should always verify that service providers are properly licensed and insured to conduct business. Service providers like mortgage lenders, appraisers, home inspectors, home improvement contractors, plumbers, electricians, and HVAC contractors need to be licensed. In Maryland, most licensing information can be accessed at http://www.dllr.state.md.us/license/ and then choose the respective industry/profession. Title agents are licensed by the Maryland Insurance Administration.
In addition, many home improvement projects need to be done with permits issued by your local government permit office. Ask your contractor for details or check with your local permit office.