Mail to your clients often.
Snail mail or email?
Either way will work; just make sure you are communicating in the clients preferred method of communication.
Some clients will prefer to receive email, some snail mail and other would like a phone call from you.
Make your clients exclusive offers.
Invite them to after hour closed-door events.
Send pre-public announcements.
Mail endorsement letters of businesses your recommended.
Stay in constant contact with your clients, or you'll leave an opening for your competitors to walk in.
Budget weekly to contact a portion of your client list. $50 - $100 a week
You'll be gald you added client calls to your plans