One book I've enjoyed which equips confidence is "Thanks for the Feedback." It's a book by Douglas Stone & Sheila Heen of the Harvard Negotiation Project.
Prepare to read one chapter every few days. It's a heavy read. Well written, it's an abundance of information: you may need to take time for brain rewiring as I did.
Thanks for the Feedback - http://www.amazon.com/Thanks-Feedback-Science-Receiving-Well...