Putting people in a genuine hypnotic state (where they will do what you say even if they really didn't wan't to) is so difficult that many respectable psychologists say it effectively doesn't exist. However you can, under controlled settings with an actively cooperating suggestable person, mess with their head to a certain extent by effecting what they can remember and implanting impulses.
When it comes to a simple conversational exchange the best you can do is the power of suggestion, that is you suggest they do something and if they already want to do it, or don't mind and want to be obliging, they will. Even stage 'hypnotists' are essentially manipulating people though their general desire to please and oblige--and their own belief that they are being hypnotised. Under most settings people will tend to do what you say and there are ways to strengthen that tendency. It's just not kosher to pretend it is anything like a hypnotic state.