I believe you need to find an electronic way to get customer reviews online so people can see the work you have done, and how pleased they were with that work. I am not sure what alternatives there are out there to doing that - from a small business perspective - on Facebook.

Also advertising online through the Yellow Pages in your local area would be useful.

Undercutting the bigger competition is smart as you are a one man shop. Make sure you “pay yourself first” meaning you don’t take on jobs that will lose money (your time).