The most efficient method would be to apply a pre-printed Post-It note to the front door of each house in a targeted geographic area. These could be printed to look like a reminder note to self. "Remember to call cleaning service. 555-5555."

Or you could hang traditional doorknob hangers on all the doorknobs in an area. Geographic targeting allows you to reduce your driving time between customers and increases the efficiency of your workload scheduling.

Repeat targeting the same geographic areas every 60 to 90 days. You're going to be surprised at how many customers will call you for a quote after receiving the same message for the third, fourth or fifth time.