Things to do for proper anal sex

Good news - Anal sex, properly done, isn't painful for most people.
Bad news - A lot of people don't do it properly.

Keep these things in mind before or during anal sex and you will surely enjoy it.

1. Go slow and use lots of lube. Everyone says "go slow and use lots of lube" when they talk about anal sex. The thing that most folks don't emphasize is what "go slow" means. "Go slow" doesn't mean "take ten seconds for penetration" or even "take two minutes for penetration." It may, if you're inexperienced, mean "take half an hour for penetration." Seriously, slow means slow.
2. Practice first! Fingers, a small dildo, a butt plug--these are awesome things to practice with. Practice with yourself. Get accustomed to what it feels like.
3. If it starts to hurt, stop. If necessary, withdraw. Give your body time to adjust. Start again when the discomfort goes away.
4. Relax. Again, this is something everyone says but a lot of folks don't explain. With most muscles in your body, the muscle's default state is relaxed and you have to do work to make the muscle tighten. With the sphincter in the anus, its default state is constricted and you have to do work to make it relax. This is where practicing on yourself really helps. Tighten the muscles in your buttocks as you learn how to make the anus relax. Try pushing. It might take a bit of practice to get the hang of it.
5. Take your time! It's not a race. Anal sex takes a while to get used to. Don't be discouraged if you don't make it work right away. Patience is the name of the game.

How to be clean for anal sex :

1. Eat healthy meals that day
2. Go to the bathroom 30-60 minutes beforehand
3. Use an anal douche to gently get water up there.  Hold it for a few seconds and release.  (Only  repeat that once or twice.)  (Note: Avoid shower extensions. With those things,  you simply can't control how much water is going up there or the pressure at which it's being shot up there.)
4. Wait about 15-20 minutes after douching to ensure all the excess water has drained (or that you don't need to use the toilet again). 
5. Take a shower.

Bonus note :

Use FC2 female condom.