Watching people works the best for me. See what they do and how they act. Consider old friends, new friends, old spouses or lovers, your parents, grandparents, aunts, uncles and cousins. Listen to what they say and see what they do. I have training is psychology. But often people don't react like the text books say. A psychology book could provide some insights though. I would just keep in mind that it is just someone's opinion.