Pick up Persuasion Engineering by Richard Bandler. Awesome and easy to read and fun book
Richard is awesome. I studied under some of his Master Trainers. The index in his book Transformations breaks down Influence as well. In his early years, Anthony Robbins used to give credit to Richard Bandler and John Grinder for the tech. Then he started trying to give people the impresssion that it was his own. I was a staff member for all of Tony's seminars in Los Angeles and OC for 7 years. I also staffed his Mastery program. But when he stopped giving credit to Richard and John, I stopped.
Influence: The Psychology of Persuasion by Robert B. Cialdini is also very good.