How well I present seems to be inversely correlated to how stressed I am before the presentation. Most of my prep time is usually calming myself down and trying not to think about anything except what my intent is: to share what I know with others and learn from them if I can. Practicing that level of honesty usually works out in a public setting, regardless of what insanity occurs with projectors, laptops, Internet connections and the like.
Oh, also, if you want to do a demo, do a screen recording! Movies are much less prone to failure.
Great idea about the screen recording. I'll incorporate some of your ideas into Friday's post.
The idea of focusing on the core of what you're doing is an important one. Looking back, another mistake I made was focusing on the presentation, rather than the chance to get to share a wonderful idea with people who could give good feed back.