Research hypnosis. Search online and in your local library and bookstore. Dozens of writers have described what hypnosis is and what how it can be used in varying levels of discourse and detail. You should not make the decision to study hypnosis based on on portrayals in the media. Stage hypnotists tend to pick members from their audience who are the most suggestible; only about ten to fifteen percent of the population are considered somnambulists who go into deep trance on their first try. Most of the people you are likely to meet as a hypnotist are medium-trance subjects (cataleptics) who require multiple sessions and/or specialized inductions to achieve trances deep enough to take posthypnotic suggestions.
Read interviews with hypnotists to help you determine what specialty you want to focus on. If you specialize as a medical hypnotist, you are likely to work on staff at a hospital or clinic. This requires extensive training and knowledge, but it is one way to become a hypnotist and earn a steady paycheck. You may help burn victims recover faster, teach patients to manage their pain, provide anesthesia without drugs, assist in childbirth or help patients change harmful habits. If you become a stage hypnotist, you will need to get an agent and be ready to do a lot of traveling, because the steadiest work is performing at county fairs and college and high school assemblies; only the top veterans work in Las Vegas or on television. Both of these paths require you to be an entrepreneur. You will have to market and promote yourself, negotiate contracts, handle billing and possibly book rental spaces for shows or classes.
Arrange to meet a hypnotist and ask your own questions. This allows you to see how a hypnotist balances his job with other demands of his or her life. You may be surprised to learn how little of their time is spent doing trance work compared to marketing. The hypnotist may talk to you about "hypnotic wash"-- the tendency for hypnotists to be affected by the suggestions they give their subjects. You may also get suggestions for more books to read or other hypnotists to talk to.
Find a hypnosis school associated with a reputable certifying organization. Unlike the AMA for doctors or the American Bar Association for lawyers, there is no single professional organization for hypnotists, so you will have to check out the training requirements and standards for any you consider. If there are no schools within a reasonable commuting distance from your home, you may need to consider starting with a correspondence course or arranging to live near your school during the training. Some schools offer three-day certification programs; some require hundreds of hours of classes followed by several hundred hours of supervised residency.
Practice during and after your classes. During your training, you will be introduced to the different stages of hypnosis (agreement, induction, deepening, suggestions), different tests or "convincers" to help subjects realize they are in trance, interview methods for matching different induction styles to different types of personalities, successful suggestion formulas and many other skills. You will probably get the chance to practice techniques with your classmates. This usually means that you must to be willing to be hypnotized as well, which can be very beneficial when you need to describe what trance is like to your subjects.