However, I don't have much to compare it to last year as we only did a small marketing campaign of 800 letters for 3 months.  

Since you don't have a real lease with this woman, look up eviction laws and follow to the letter.

Third, send a letter to the address where payments were being made.

What do the letters "(F)" and "(S)" signify at the end of Price?)

You can dig it out here, it just takes longer. 

Hey BP,I am super pumped that I had my first round of yellow letters go out to Probate Leads here in Houston...and I have start receiving my first few calls back!

I had a brief adventure with yellow letters for the purpose of wholesaling with a brother-in-law in early 2014; I learned a lot doing that, but ultimately we weren't fully committed and it fizzled out after sending out two waves of letters and talking to only a handful of people.

Does anyone have a template for letter they would like to share? 

I got my very first call back from potential seller after he got the yellow letter I sent just three days ago.

Hi guys,2 weeks after have sent my first DM batch of aprox 240 letters I have the partial results.3 calls, one that already sold and two good ones.