I know this has been discussed on the site in several different ways (scheduling, billing, etc...). Just wanted to add a great way to communicate with clients is via email. It does not exactly take the place of human interaction, but don't be afraid to ask your clients for their email address when gathering their contact information. Every so often you can send a simple "blast" to all of your clients thanking them, letting them know about seasonal services, reminders, etc... If you have 75 year old clients, asking for an email address might produce an odd look, but if your clients are doctors, lawyers, young professionals, and even property managers, they would probably be glad to give you their email address - convenient for both.