Hypnosis should only be undertaken by the most dedicated and thorough of people as a little bit of knowledge, as always is dangerous.
There is also a whole other language you have to learn as good suggestions use linguistic patterns to highten their affect, such as Phonetic ambiguity.
Some will tell you there are two main types... its not true, all are as good as each other but you have to learn how to judge what a person needs and adapt to that.
Jonathon chase has the best books in the business buy them read them, he is one of the best.
What ever you do, learn from people in the know, not the people who have written on here before me.
Milton Erickson is the father of all modern hypnosis and he said "There is no such thing as a person who cant be hypnotized, there are only inflexible hypnotists". To be a good hynotist you need to be as flexible in yourself as no 2 people are the same.
One more thing.. Learn what to do if something goes wrong. Please dont fly of and try the first thing you learn. learn as much as you can first.. then try them.. People can have hidden SEE (Significan Emontional Events) that can be triggerd if the wrong thing is said. Learn how avoid triggering them, learn that what you say and how I he brain will interpret it, and most importantly learn how to reverse any SEE that you do trigger.
Learn for more about hypnosis at freedomfreedomnow.com