Hopefully you already trust the one you’re with but it's wise to: Use a condom whenever you engage in anal sex. You should also never go from anus to mouth, or anus to vagina, without washing carefully (and changing condoms) in between.
The anus has no natural lubrication, so you'll need to use plenty of lubricant. Avoid lubricants that contain analgestitics, pain is your friend here and numbing the area can be dangerous.
Encourage your partner to take deep breaths and communicate his or her feelings aloud because this is a two way street.
You might want to try incorporating anal toy play into your love life before jumping to anal intercourse. Of course the best sex toy of all is your fingers!
Pain is the body’s way of telling us that something is not right and it's something we should all listen to. If you are the one receiving anal stimulation make sure you tell your partner if it hurts. Take a break and maybe try again.
Once you are ready to try anal sex, slow things down and take it easy. This is not a race and the experience will be much more enjoyable if you do.
Always allow the partner who is receiving the anal to set the depth and pace. See 5
According to Clitical members the favorite position for anal sex is doggie style.
Don't forget to stimulate other areas of the body while participating in anal sex. A little clitoral stimulation can go a long way to making the experience more satisfying for both partners.
If things don't feel right it's okay to stop, take a break and start again. This is supposed to be fun after all!