Take a Tip (or Ten) from Toastmasters!
Toastmasters International lets you download a free PDF "Ten Tips for Successful Public Speaking". Here's an excerpt from their tenth tip:
"Gain experience. Experience builds confidence, which is the key to effective speaking. "
Yep. You can sit down, research and design a PowerPoint presentation or practice a speech in front of a mirror all day long....you can read blogs like this one, or tinker with tutorials....
...but nothin' beats experience.
Get your bad self in front of an audience. Get experience. Start presenting!