Usually the only thing I have to do to prepare my slut is to start with 2 fingers, then 3, then 4, then fist. Only takes a minute or two from 2 fingers to fist. She loves it and her orgasms are pretty intense when I fist her. When we fuck after that it feels just as tight as she did before hand. It's amazing how elastic a women's pussy can be. We're 50/50 on who decideds to fist, sometimes I just feel like it, other times she'll tell me to use more fingers, and that's the give-away she wants a fist.