Advice for direct mail?

[Henry Lazerow]

Looking to start a direct mail campaign. This will be my first time doing direct mail so open to any advice! 

I am planning to do 8 sets of mailings over 16 weeks, does this sound like a good frequency? I have recently done a bunch of deals in the same area so am thinking about doing a few just sold flyers, then free appraisal, flyer with all the properties I brokered for 2018, etc. targeting that area in Chicago. The goal of this is to get more brokerage listings not to wholesale any of these deals. I am about to pass $10 million in 2-4 unit sales for 2018 so would like to highlight the fact I specialize in 2-4 units, any advice for marketing materials? Are you seeing better results with postcards or letters in an envelope? Where are people sourcing their lists of addresses to send to? I have looked at List Source but only got a small number of 2-4 unit names in my zip codes. Feel free to PM. 

Thank you,