Can't speak for anyone else, but I'm not sure what you're asking. If you mean the "Approval Rate" or whatever it is in the Demographics window, I wouldn't worry about that, that metric has been full of crap since Civ1. I'm sure there's some mathematical formula, and the code-divers could probably tell you how to maximize it, but I just laugh whenever I see that number.
However, if you're referring to diplomacy, please give us some specifics, because that's a whole big complicated animal.