Practice, practice, practice.
Every public speaking book talks about it (this one and this one for example). Every presentation design and public speaker blogger repeats it all the time. So much so, that it is tempting just to speed read over the paragraph to get to the cool stuff about adding that 3D shadow to your slide. "Hey, I am a confident speaker, ticked that box"
Some sentences to get you to change your mind:
- Steve Jobs practices for roughly 2 days full time before his keynotes
- When your are confident you know your stuff, test yourself: close the office door and do the first 3 slides as if it were the real thing. Did that came out brilliantly? If it did, congratulations, because this first test run is exactly how your opening would have come out in front of a large audience. If it did not go that well, congratulations, you just got yourself a good incentive to start practicing.
- Spontaneity does not equal winging your story, a good movie actress can only come across spontaneous if she now her stuff inside out
- If you know your material inside out, all the presentation professional's talk about cutting bullet points and clutter will come naturally to you: you do not need on-screen speaker notes anymore.