Here's the experiance i have garnered from having received it at an early age.
1.) Clean yourself out first: use a very strong coffee enema or two first. A coffee enema gives me a buzz and total body relaxation. Plus it will clean you out.
2.) have the other person give you a nice full body, hot oil massage.
3.) lay down on your back have the person who will be penetrating you finger your g-spot while sucking on your clit. This way you are pleasured first. Adding more relaxation and pleasure.
4.) when ready, still laying on your back, the other person should start massaging lube into your backside. Starting with 1 finger, then after a minute or so, add a second finger, then after a few minutes add a third. Once you tell them you are ready,
5.) they should slowly insert it ( penis, vibrator, dildo, strap-on) into you. Have them stop once they are in in case there is discomfort. Which stopping for a few minutes will help alleviate.
6.) take it slowly. Allow yourself to enjoy the fun.
7.) afterwards, take another enema to clean out his cum, or if it was from a vibrator, dildo, or strap-on, take another enema just because.
8.) return the favor and do the same to your partner.