One way that I've found on how to go about hypnosis pre-talk that I now prefer (for people who have been hypnotized before, anyways) is just laying out everything that I'm into in regards to hypnosis and talking about where I'm strongest and the most effective, often in very long messages so I can really focus on being an open book and so I don't get sidetracked by conversation. This includes the fact that I find hypnosis inherently sexual, all my kinks, what I find hot about hypnosis, specific things with hypnosis I like to do (e.g. goddess/slave dynamics, memory play, teasing and orgasm denial, etc.), and so on. From there, the subject is able to go through it all and say what they like/respond to well, what they don't like, and it makes talking about the specifics and boundaries much easier for the both of us, I feel. I've only done this with a couple of people so far because I've only started doing this recently but the people I have done this with have really appreciated it. It gives me very clear areas of what I can and cannot do, and thus makes it much easier to come up with ideas on what to do with the person already.
I'm curious though on what other people do for pre-talk, both from hypnotists and subjects. I'm someone who does my best to make my subjects feel safe, comfortable, and relaxed, and so pre-talk has always been very important to me and it's something I always want to improve on.