My mailings have been too sporadic; tough to track what works well. I just created an account with InfoUSA so I can develop targeted mailing lists. My plan for 2009 is to have the graphic designer with whom I work craft four different postcards that I'll send quarterly. With InfoUSA, you can get 100 free leads so I did a test list with very specific criteria. The list looked real good as far as hitting the criteria I established. I also saw a few existing clients on the list and they definitely fit the criteria so that was a big plus with regard to the quality of the list.
My other plan is to be a lot more proactive when it comes to getting email addresses and will be trying monthly specials that are available only to those receiving the emails. If a person signs on to receive the monthly emails, I can omit that person from the postcard mailings. That way the postcards are working to attract new clients, or at least creating new contacts. Hopefully this makes better use of the money spent on the mailings.