Paul Vitale has written a complete textbook for people who need to sell something: salepeople, certainly, but also job hunters, entrepreneurs, and all the many other people whose jobs involve persuasive communication.
Vitale begins with basic issues that affect your confidence, from attitude to hairstyle and shoes. He moves on to practical, step by step suggestions for getting past gatekeepers and on to the decision makers, with detailed instructions for structuring your sales call and following up.
The book finishes up with a reference section, pages on specific issues in sales and customer service including everything from ways to psych yourself up before giving a presentation to strategies for coping with angry customers.
One of the things I liked best about this book is the fact that it never lost sight of the importance of respectful, authentic communication. You don't have to be a manipulative shark to make the sale, and Vitale's approach is far from that old-school predatory take on sales.