The More you Read about it, the complex it gets
Psychology is one such subject where not even Freud could claim a mastery over.
As I read more, I am convinced there is no better teacher about people skills & negotiations than real life experience & perhaps that's why during MBA & Campus Placement Interviews, they prefer those who organized college Fest's, who negotiated rates, who did all the dirty work of getting things done, getting deals settled and all the hardcore sales stuff.
As with each passing experience their intuition became sharper better and their people reading skills were brighter than their peers.
Same thing can be interpreted so differently by 3 different individuals. Depending upon their past experience & their level of self esteem , their mood and other variables.
Take for example a delay in replying during a business or salary or contract negotiations.
A self confident, high self esteem person will interpret delay in reply as a sign of other person probably being Busy.
A Feeling Low person would interpret it as another person ignoring him/her.
A Nice Past Experience where the person got good results by waiting will be more open and optimistic about having to wait for a reply from an opposite party.
A Manager's goal is to read and predict all that
When negotiating with juniors with end customers with senior management
In any & every context, It feels like it's just better to not remember any principle and go by your gut feeling but then again, One's gut feeling is nothing but one's set of past experiences that morphed one's nature & attitude and made him/her adept or inept at skills & negotiations.
So what's the golden rule? The key to unlock the power to read minds?
Nothing except some good books and a higher exposure to apply all those principles and develop an intuition about what works & what doesn't.