Since anal sex is so trendy these days, and you are probably reading this because you also like it or are planning to try it someday, let me begin with the first basic steps that you need to be aware of before you would start your games, and you should tell your partner about it ahead of time.
There are two ways to clean her anus, one being diet, and the other being enema. Both of these is the responsibility of the person who will let someone penetrate his or her anus. First of all, let me begin with the quicker way or preparation. When a person is giving him- or herself an enema, it should always be done with about a half liter or three cups of lukewarm water to cleanse the anus – not the entire colon – and it should be done in private, since it is not the most pleasant experience for a partner. The water should be infused via the rectum, and should be kept in as long as possible before it would be let out into the toilet. It takes from 5 to 20 minutes at most.
The method that is somewhat more pleasant is nothing per os diet for about 8 hours before penetration. It originally means that nothing can be consumed orally, but in this case, water is allowed.
Still, the person who penetrates an anus should keep in mind that even if it is clean, it can contain bacteria that should never get into the vagina, so anal penetration cannot be followed by vaginal penetration without properly cleaning it first. Probably it is needless to mention, that the penis should be cleaned and disinfected after the coitus, to prevent any possible infections, as well.