I think they work if you believe they work. You can try it and see if it works for you because in my opinion different things work for different people.
I have tried guided "self" hypnoses by listening hypnoses that are on youtube. There are some people there who post their own hypnoses videos and are offering them for free. There is quite popular hypnotist Michael Sealey who posts different sessions about self-esteem, confidence, self love and other topics.
I do self hypnosis by myself now and it's quite fun
I am using exercises from Seth and first I imagine how my body is stretching outside of me (like my astral body) and I have a very good massage of joints and muscles while doing it. I also do a little work out like that for my muscles and it helps with maintaining my belly packs. By that point I am really relaxed and I start using self talk, kind of like affirmations. It really came naturally actually and I didn't think about it. I just thought that if I can manipulate my body like that, I can manipulate my mind and I imagine different things, like imagining my left and right brain connecting and all kinds of different things. I am imagining that my serotonin levels are boosting. I trust that my imagination brings to me what I need. So I just kind of go with the flow, with no written "program" before doing it.
Have fun with it