You will be told to sit or lie down somewhere, get comfortable and close your eyes. The hypnotherapist will then use their methods to get you in a a trance like suggestable state. This has been quite nicely described as feeling similar to the state of mindlessness people occasionally experience when driving a car without consciously thinking, just much more relaxed.
In 1923, Griffith developed and taught the first sports psychology university courses (“Psychology and Athletics”) at the University of Illinois, and he came to be known as “The Father of Sports Psychology” in the United States, as a result of his pioneering achievements in that area. However, he is also known as “The prophet without disciples”, since none of his students continued with sports psychology, and his work started to receive attention only from the 1960s 
How well hypnosis works to help people stop smoking depends on who you ask. Study results have been mixed. In 2010, a systematic review of published studies found that there wasn't enough evidence to support the use of hypnosis. Another review published in 2012 said that studies do support a possible benefit from the use of hypnosis. In discussing alternative methods for quitting smoking on its web site, the American Cancer Society says that while controlled studies have not supported the effectiveness of hypnosis, there is anecdotal evidence that some people have been helped.
There are a number of articles, books, and audio guides available for free or purchase online that can give you pointers or guides for self hypnosis. There are also hundreds of self hypnosis apps available for download. However, it is important to note that many of these apps have not been scientifically tested, and are not proven to work, but if they help relax you, there’s little downside.
Look for a hypnotherapist who is a member of the American Society of Clinical Hypnosis (ASCH) or the Society for Clinical and Experimental Hypnosis. To be a member of either of these organizations, a hypnotherapist must have a doctorate level degree in medicine, dentistry, or psychology, or a master’s degree in nursing, social work, psychology, or marital/family therapy plus a specific number of hours of approved training in hypnotherapy. In some cases, accredited, doctoral-level practitioners of alternative health care, such traditional Chinese medicine, may also be approved for membership. Of course, in addition to looking at qualifications, you should also find a hypnotherapist with whom you feel confident and comfortable in a therapeutic relationship.