Direct mail - what do you say next?

[DuWayne Jones]

I just sent out my first wave of direct mail looking for potential sellers. The first wave was a typed letter with my hand-written signature and the address on the envelope written by hand.  For contact info I provided my name, a phone number (via Google voice) and my email address.  I'm getting ready for wave two, and expecting to send letters or postcards once a month for several months. For future mailings - should the message or format be primarily the same, or should it be modified each time? What works best for those of you who have had success with direct mail?

Thank you for your advice.