Am I over complicating direct marketing or underestimating it?

[Jeff Gebhart]

We are experienced landlords and have done a few flips.  We have never done direct marketing for properties but want to.  The more I read, the more I get confused. I realize there is no recipe / cook book for what will work.  This is the parameters I was searching in our desired area (using Listsource.com)

Specific County
30-100% equity
Last market sale date 4/26/08 - 4/26/2011
Year built 1950-1998
Exclued corporate owned

It stated there were 658 properties for my search.  That seems very small of a market.  With a company like yellowletterhq.com I could have all those properties recieve mail in the first day.  Right????  

My questions are : 

1) Is my criteria too specific?
2)  How many letters should I be sending out a day/week?  I know this is budget specific.  My goal is to close one property a month.  I have heard some spend on average about $750-$1000 per every deal they close.  

3)  How often should I send out to this each list?  1/month? 1/other month??
4) ANY advice that would help me launch my first campaign would be helpful.  My head is spinning!!!

Thanks!!!

Jeff