The book, "Influence: The Psychology of Persuasion," by Robert Cialdini is a book I wish I had read long ago. I'm pretty sure this will now be a book I  read again and again. The book walks through the six universal principals of persuasion with practical advice. Psychology and consumer behavior are fascinating to me and this book provides great insights and practical details about influence. I'm going to recommend this to every manager and leader I know.