You have to start with the ideal scenario, which I assume would be introducing your partner to hypno and he/she gets excited by it. I've done this, and here's how I would recommend approaching it:
1. Gauge how open your partner is to kink, roleplay, and new experiences in general. I usually just make a joke about it. For example, if some TV show or movie has a scene with BDSM, I might say, "I'd definitely let *you* tie me up!"
2. Express to your partner that giving him/her control excites you. This usually makes the person curious and ask about it, like "What sorts of things does that involve?" Be ready to describe some very simple activity/scene that you would enjoy. For example, "Like if from now until midnight, I must start and stop giving you head on command, as long as we're in a safe, private place."
3. Try more things until the idea is comfortable. There are plenty of easy ones, such as, "How about I can't orgasm until you give me permission?" Or, "What if I'm required to address you using an honorific of your choosing, like 'your highness?'"
4. If things go well and you have fun, introduce the topic of hypnosis. You could test the waters by watching a show or movie that mentions hypnosis, bring up an "interesting article" you just read about it, or attend an event with a live stage hypnosis show. See if your partner expresses interest.
5. Tell your partner that you've been hypnotized recreationally. This nearly always leads to curiosity and follow-up questions. Your partner will almost certainly want to know what it's like and whether it really works. Say you thought it was great and would definitely do it more!
6. Tell your partner that you would enjoy going into trace for him/her. Lower the barrier to entry by recommending you listen to a file that implants triggers your partner can use later, or if you're both down, you could try a couples file together.
7. Graduate to where you listen to an induction only, and then your partner takes over. Then have your partner suggest a trance trigger. Play aroundPost too long. Click here to view the full text.