One of my favorite books, which I often recommend to others, is The Power of Nice by Linda Kaplan Thaler and Robin Koval.
In the book, Kaplan Thaler and Koval illustrate the surprising power of nice with an array of real-life examples from the business arena as well as from their personal lives. Most important, they present a plan of action covering everything from creating a positive impression to sweetening the pot to turning enemies to allies.