The problem with self hypnosis is that, in the beginning, you use your conscious mind to bypass the critical factor of the conscious mind. This is a bit like trying to lift yourself up in a bucket. It works a lot better when you are able to direct yourself without thinking with your conscious mind, because the goal is to bypass the conscious mind. So after a lot of practice, the directions become second nature in which case you don't engage the conscious mind and so self hypnosis is much more effective. So, I wouldn't buy a book on the subject, I would visit a very experienced hypnotherapist and get him/her to condition you to drop into hypnosis and give yourself suggestion linked to a trigger (anchor) such as pushing your thumb and index finger together. Hope this long winded answer helps!