There's a lot of great content on the web, but picking the wheat from the chaff can be a chore. (I'll be sharing any great content I find on this blog.)
Here's some advice almost any professional can use; I wish it had it a year ago. How to Give a Great Presentation by Jason Calacanis. Though the subject is "pitching a startup to investors", 85% of it can be applied to any presentation. The video is over twenty minutes, or you can just read the abstract. But, the color commentary in the video makes it worth the time invested.