I have almost always used direct mail as a part of the marketing effort. First you need to know what your realistic target market is actually. Then you need to get lists from a credit information supplier that is targeted to the group you should be targeting. Then the mailing should be written to appeal to that target market group.
I really like direct mail and so do our clients (people with related or captive finance companies in manufactured housing) because it works really well when you understand what you are doing. We have one client (a large community group) that averages seven new homes a week in sales from his direct mail alone.
I hope the two white papers I sent you via email help.