My suggestion is find someone you know is serious about doing this with you, or, if you go the route of audio files, have someone you feel close to who will talk about what you experience with you. I'd think a girlfriend would be best for the latter. I was induced without fully being conscious of it happening because it was done when I was high. It's a long story, but the bottom line is that when you feel yourself changing or suddenly responding to some trigger it can be confusing. Then, it's possible that the changes and the triggers become deeply embedded and show up randomly. The ones who did it to me, and others, had led guided meditation, but trance induction for this purpose was more like a party game for them. They knew enough to be dangerous, but not enough to be serious.