I suppose most of my readers know by now that when I'm speaking in public I push the limits most of the time to make sure my audience stays awake. It should be no surprise to you then that I will attack another common old style snoozer technique (and I know I will get letters from educational theory folks, but that is OK) . . . that is, telling the participants what you are going to cover during your presentation.
I say let 'em figure it out as you go. If they think they know where you are going during a public speaking engagement, then it is easy for them to 'zone out' since they 'think' they know what you are going to say. The way I do it is to make them wonder, 'What in the heck is he going to do next?,' which forces them to stay alert to find out.