First time trying anal? Help?

How do I prepare for anal? How do I shave my bum hahaha. On a serious note, closest thing to anal I've done is when someone tried to shove it in wrong hole during sex. Me and bf have never tried it or even with other people. Very comfortable with eachother, been with me since he was a virgin so very sexually active. He wants to try anal and so do I, but I'm scared of pooping. How can we make it hurt less and make sure it's a clean job