Agreed. Referrals are #1, and you should offer some sort of discount or free stuff.
But that requires the customer to work for you and that may or may not happen.
Don't be afraid to knock on doors and introduce yourself.
Just keep your eye open for a good opportunity to show up.
If there is a dull blade job, crooked stripes, no edging, ect., knock on the door and tell them who you are, and that you noticed the "problem" and to feel free to call if you need help.
If you can win them over, they will call you before anyone else.
Keep cards in your pocket all the time.