Jenn,
Welcome to BP. I don't have experience with mailers but I can give you help with the initial phone call when they respond to your ad.
Make a second line with some kind of distinctive ring or announcement so you know when it's an ad call. I use a cloud based phone system that shows me the number dialed before I answer the call so I always know which ad they are responding to and I answer appropriately.
I would write out a simple call script that establishes the framework for collecting a lead and deciding if they are a qualified prospect. The initial call is an information gathering exercise. Have a form handy that you can fill in as you go that has all the pertinent questions. Use a web form or set up a form on your computer that you can save the data and use later.
Most callers will start asking questions to see if you are a qualified buyer. You want to take control of the call from the very beginning. Let them know that you have strict buying criteria and the only way to know if their property qualifies is to go through the questions.
Get facts about the owner with complete contact info including email. Get the facts about property, how long they have owned why they are considering selling, how much they think it might be worth, what they owe, who the lenders are, who is on title etc..
Don't decide what to do with lead until you have all the facts and have had a chance to do some analysis. Part of real estate investing is building your database of property owners. Always collect a complete lead before making any disposition.
Be polite but non-committal. Limit the amount of information that you give and encourage your prospect to talk about himself.
Here is how my incoming call script for property sellers looks:
Get the facts, end the call by letting them know that you will start the review process immediately and you will let them know as soon as you do some homework. Don't make any offers over the phone and don't commit yourself until you are sure.
Using a set script with a structure to collect a lead will help you to be consistent and populating your database with leads keeps the hopper full.
Best of luck.
Ted