One of the most interesting things about Ekman’s work is that these skills can be learned. In “Emotions Revealed” Ekman uses detailed pictures of his daughter making tiny changes to her face, and explains how this results in vast differences in expression. This is backed up with news photos of people expressing the same emotions. Ekman explains how we can even generate emotions in ourselves just by moving our facial muscles. The back of the book gives a quiz on reading facial expressions, which Ekman suggests taking both before and after reading the book.
You can find more info on Paul Ekman, including extensive interviews with him, on his website.