The first book I read about public speaking is still my favourite on the subject. It dives into the topic of practice and why people who give presentations feel it is beneath them or are embarrassed to do so. Practice is one of the most important ways to become a better public speaker.
Other invaluable tips include being on time, checking the audiovisual, and looking at the room and getting used to it. Also, how to work a tough room, the science of not boring people, how to survive the attack of the butterflies, and what to do when things go wrong