How to effectively use direct mail marketing

[Jeet Sangha]

It’s been a little while since I have consistently used direct mail marketing in my business. So, I wanted to put a couple of questions out there. First, what type or response rate are you seeing? Second, what criteria is most effective to filter the list for motivated sellers these days? Third, what is a good source to pull the list? 
lastly, are yellow letters or postcards still effective?