The most important element in any kind of inspirational speaking is to believe in what you are communicating. Simply put, its PASSION.
#1 Have PASSION for a topic or concept then craft it into an organized talk
#2 Practice SPEAKING as much as you can to polish your skills. Different audiences respond differently to content. The more you are exposed to different situations, the better your response will be with the unexpected.
#3 Get CREATIVE. Avoid doing the “same old, same old” type of canned talk. Upgrade your style, approach and delivery methodology. Do not be afraid to be unique and interesting…that is exactly what makes people LISTEN. 
Add these tips to your personal development plan and you will be the next keynote speaker before no time!
For more information on creating top notch presentations check out article Present Your Ideas with Precision, Poise and Heart (part of Do Your Own Thing, Little Business, Big Advice e-book)