I don't call them.

I send a quarterly email newsletter. It's involves less pressure than a phone call, but you have to pay for the newsletter service and write the letter. Sometimes it can be pretty tough to think of things to say in the letter. I try to provide useful information rather than sales messages. Its already implied that they call you for service.

In addition to the newsletter I always leave something at the customer's house: sticky pads with my logo, fridge magnets with logo, free spotter, etc.

These things work. Many customers tell me they remembered how to contact me again because of something I left at the house. Other customers have contacted me through a link in the newsletter to schedule additional cleaning. You won't see results the next day, however. You will notice instead that eight to twelve months later, your repeat business and referrals have gone way up.