Embarassing question about anal

So I've had anal before, like the total said. And I enjoyed it. My bf did too. But we did it not knowing exactly what to do. So um…stuff got everywhere. To say in the most juvenile way. I was wonderibg how can you have anal with this not EVER happening again? I was thinking just have it in the shower. But when in the world will you almost always have a shower avalible for you to have anal sex in when you want to have it? 
Overall: how do you have proper Anal sex without getting "stuff" everywhere?