Jim Munro: Here are two quotes stolen from the web, Jonathan.
"A referral from every client and every client from a referral." and
"The purpose of a business is to create a mutually beneficial relationship between itself and those it serves. If it does that well, it will be around tomorrow to do it some more."
Let me know if they work and I might try myself. :)
David Ogletree: Offer training. They find out how hard it is they hire you to do the work and they become better clients because they know what you are doing.
There is no big secret to marketing just elbow grease.