The techniques used to induce hypnosis share common features. The most important consideration is that the person to be hypnotized (the
subject) be willing and cooperative and that he trust in the hypnotist.
(see will vs. imagination)

The subject is invited to relax in comfort and to fix his gaze on some object or in other cases to close their eyes and concentrate on the voice of the hypnotist excluding all else.
The hypnotist continues to suggest, usually in a low, quiet voice, that the subject's relaxation will increase and that his eyes will grow tired. Suggestions may be given to relax the various parts of the body. Soon the subject's eyes do show signs of fatigue, and the hypnotist suggests that they will close. The subject allows his eyes to close and then begins to show signs of profound relaxation, such as limpness and deep breathing.

He has entered the state of hypnotic trance. A person's responsiveness to being hypnotized is greatest when he believes that he can be hypnotized, that the hypnotist is competent and trustworthy, and that the undertaking is safe, appropriate, and congruent with his wishes. Therefore induction is generally preceded by the establishment of suitable rapport between
subject and hypnotist.

  Ordinary inductions of hypnosis begin with simple suggestions made by the hypnotist that will almost inevitably be accepted by all subjects.
At this stage neither subject nor hypnotist can readily tell whether the subject's behavior constitutes a hypnotic response or mere cooperation. Then, gradually, suggestions are given that demand increasing distortion of perception or memory (e.g., that it is difficult or impossible for the subject to open his eyes). Other methods of induction may be used. The process may take considerable time or only a few seconds.
The resulting hypnotic phenomena differ from one subject to another and from one trance to another, depending upon the purposes to be served and the depth of the trance. Hypnosis is a phenomenon of degrees, ranging from light to profound trance states but with no fixed constancy.

    Ordinarily, however, all trance behavior is characterized by a simplicity, a directness, and a literalness of understanding, action, and emotional response that are suggestive of childhood. The surprising abilities displayed by some hypnotized persons seems to derive partly from the restriction of their attention to the task or situation at hand and their consequent freedom from the ordinary conscious tendency to orient constantly to distracting, even irrelevant, events.
  Suggestibility, a state of greatly enhanced receptiveness and responsiveness to suggestions and stimuli presented by the hypnotist, constitutes the central phenomenon of hypnosis. Appropriate suggestions by the hypnotist can induce a remarkably wide range of psychological, sensory, and motor responses from persons who are deeply
hypnotized.
  By acceptance of and response to suggestions, the subject can become deaf, blind, paralyzed, hallucinated, delusional, amnesic, or impervious to pain or to uncomfortable body postures, or he can display various behavioral responses that he regards as reasonable or desirable in the given situation that has been suggested to him by the hypnotist.
One fascinating manifestation that can be elicited from a subject who has been in a hypnotic trance is that of posthypnotic suggestion and behavior.         By this is meant the subject's execution, at some later time, of instructions and suggestions that were given to him while he was in a trance. With adequate amnesia induced during the trance state, the individual will not be aware of the source of his impulse to perform the instructed act. Posthypnotic suggestion, however, is not a particularly powerful means for controlling behavior when compared to a person's conscious willingness to perform actions.
Many subjects seem unable to recall what happened while they were in deep hypnosis. This posthypnotic amnesia, as it is called, can either result spontaneously from deep hypnosis or it can result from suggestion by the hypnotist during the trance state. The amnesia may include all the events of the trance state or only selected items, or it may be manifested in connection with matters unrelated to the trance. Posthypnotic amnesia may be successfully removed by appropriate hypnotic suggestions.
Conversely, hyper amnesia, a memory capacity that transcends the everyday ability, is another aspect of hypnotic behavior. For example, in the trance state, the subject, by virtue of an uncritical willingness to make the effort and a freedom from inhibitions deriving from preformed judgments, can vividly remember long-forgotten, even deeply repressed experiences, recount them in extensive detail and still maintain an amnesia for them at the ordinary level of consciousness. This remarkable ability permits the recovery of memories that are otherwise unavailable to conscious awareness, and it was thus of great usefulness to Freud as he embarked on his explorations of his patients' unconsciously held memories.
See Recent findings to learn more including the link to a real (scientific) taped session