I've tried hypnosis to stop smoking several times, but it never worked for me. What I have noticed, is that I can use a form of self hypnosis on myself that works quite well for certain things for example, stopping pain, or for endurance. Yes, basically it's talking yourself into something by getting your mind to accept it, but with me it does work.
It only works on the weak minded. Every time one would come to the school for assembly I was always one of a handful of students that it wouldn't work on. However there was something I never noticed until my older stepsister, a now retired jr hs teacher, told me, that teachers NEVER attended those hypnotism assemblies, one teacher was also reserved for a study hall for us students that it didn't work on, we were excused from the rest of the assembly, so I had no idea what happenednin them, but I suspect a bit now they were initially hypnotized to obey everything they were told, this was in the 80's.