I studyied The Ericksonian training and Neuro Linguistic Programming (NLP). It's interesting to note here that every school of hypnosis will teach either one or both. I studied both. Then Conversational Hypnosis techniques by Igor Ledochowski. And from there I studied under the American School of Hypnosis, and from one of my mentors who taught me how to master the 15 minute session, the late master hypnotist Jeffrey Stevens.
I also read many books from the creators of medical hypnosis techniques who practiced medical hypnotherapy way back in the 1800's. Those creators wrote down every accomplished technique so that their readers, their students, such as myself, will have the same if not better accomplishments.