Successful hypnosis can come in a variety of different packages. Sometimes it is a very deep sense of relaxation. Sometimes it feels like you are sort of outside yourself watching the session with a detached and analytical mindset. Other times hypnosis can feel like nothing at all, you simply look up and notice 20 minutes has gone by and you've no recollection of the gap. Hypnosis can feel different from person to person and from session to session.
The key to a successful hypnosis session is very simple. Do not force it. Just as importantly, do not try to "help" it. Just follow instructions to the best of your ability. Your subconscious will keep you at whatever "depth" of hypnosis you are comfortable with.