Fast replies is great as you can have pitch perfect answers to common responses such as:
I'd like more information..
I'd like a call..
I'd like an email...
I'm not the correct person, you need to talk to..
I'm not interested
To save these simply click on the "/" dash icon in the inbox box and click on Add Replies where you can add your reply and save a title for each response so it's easy to find based on the type of response you are given.