I certainly know what you mean as I have a similar fascination with the topic. But, all things being relative. How you do that would be entirely dependent on the situation, people (personality types/background) involved, and what I wanted. There may be many similarities between scenarios but there is no cookie-cutter/onesize-fits-all answer.
Yeah I agree you have to be flexible and know how to read someone.
But and it's pretty common sense when you want something from someone in essence you're relinquishing power to someone because they could say no. In general what works best for me is to play the charm card, it's hard to explain but basically you have to appear to be smiling and be easy-going, almost carefree in your demeanor.
But you'll meet difficult people. Just yesterday I was trying to get something from someone and they wouldn't give it to me. Instead of getting upset I came up with a great lie on the spot but they didn't understand what I was trying to explain.
So I stayed cool, explained some more, behave as if it was not that important that I get the stuff I wanted after all and finally everything fell into place and I got what I was after.