What advice would you impart to a new hypnotist or subject?
Practice, practice, practice.
Inducing a trance, phrasing suggestions, knowing that to do regarding abreactions, all these things involving hypnosis must be practiced to ensure competency. All of these things are skills that can be improved with practice.
That goes equally for subjects. Not everyone is a great subject at the beginning. Being hypnotized is a skill that can be learned and improved with practice. (This I know from experience.)