Anal for the first time😱

Hi girls! My boyfriend is coming to visit me in two weeks and we want to try anal for the first time. I'm super scared because omg so many things come to mind. Do I have to have a special diet or do anything special so it all goes well? What I mean to ask is, is there anything I can do so I won't have an embarrassing story to tell my grandchildren of how I shit on their grandpas dick once? Any advice is truly appreciated. ❤️