This book explains how the miracle of powerful public speaking is achieved, and equips you to give it your best shot. There is no set formula; no two talks should be the same. The goal is for you to give the talk that only you can give. But don’t be intimidated. You may find it more natural than you think.
http://www.kurzweilai.net/ted-talks-the-official-ted-guide-to-public-speaking