Regardless of who you choose here's some common sense checks to make before hiring any kind of contractor or home improvement person, because anyone can come in here and recommend someone when in fact that someone may be them.
So here's some things to check:
1. Check the Maryland Judiciary Case Search for their company's record and their own civil and criminal records. You may also ask the contractor the names of who will be performing the work and check them too.
Maryland Judiciary Case Search
2. Check to see if they have a business license and check if it is in good standing:
Taxpayer Services
3. Check to see if they are properly licensed:
Licensing Queries - Division of Occupational and Professional Licensing
4. Check their BBB (Better Business Record):
BBB of Washington DC & Eastern PA: Home
5. Ask for references from other customers and photos of their previous work.
Just a few tips.
Anyone else have more tips to add?