Same way you do with anything new that's different from what you're used to. Do your research. Talk with him, talk with people who have done it before, find out as much detail as you can about rules, any changes you'll have to make....etc. Then after much discussion and research have more discussion with your partner about what kind of multiple session you want first and who you want to try it with. Of course do not proceed with anything you are seriously uncomfortable with. It's one thing to "try anything once" and another to do something you really don't want to do. That goes for all involved.

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"BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Will he offer me his mouth? BOY: Yes. GIRL: Will he offer me his teeth? BOY: Yes. GIRL: Will he offer me his jaws? BOY: Yes. GIRL: Will he offer me his hunger? BOY: Yes. GIRL: Again, will he offer me his hunger? BOY: Yes! GIRL: Yes. BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Yes. BOY: I bet you say that to all the boys!" -Meatloaf