I posted this book recommendation in another thread, and it's a great resource for emotional intelligence and social interactions:
Amazon.com: First Impressions: What You Don't Know About How Others See You: Books: Ann Phd Demarais,Valerie Phd White
It covers a lot of great information about how to understand and empathize with people and become friends with them.
Dr. Paul Ekman's book on understanding facial expressions is another really good book:
Amazon.com: Emotions Revealed, Second Edition: Recognizing Faces and Feelings to Improve Communication and Emotional Life: Books: Paul Ekman