The biggest discovery I made in my studies to become a hypnotist was in being able to discern other people's metaphors and use them in communicating (rather than my own).
Personal metaphors are jam packed with information and emotion.
For example, when someone talks about being part of a "club", it seems like an innocent word doesn't it, but to them the club metaphor may mean the inclusion or ostracization of a social group.
Of course, some metaphors are universally understood (especially archetypes) and can be the transport system for new instructions to the subconscious mind. I used the Warrior metaphor for my eyes-open self hypnosis: http://summonthewarrior.com and people seem to respond really well to it, myself included!