I gave an impromptu talk on black holes two days ago for the campus astronomical society, and because I was given notice only the evening before the talk, I could not prepare as well as I ought to. I had only two hours to prepare for a 1 hour-long talk, and I spent most of the time selecting images. So there was no sensible way to start and end the talk; I did organize it around the questions that appear on the first page of Taylor and Wheeler's book, Exploring Black Holes.
Looking back at it, there are a lot of things that I could have reshaped. My plan was to talk about what an observer will see and feel as he falls into the black hole. These ideas are well understood by the professional relativist (or should be) and I'm afraid I wasn't as excited as I once was when I first understood the topic. This topic may actually be better served by animation and a storyline. I'll rethink the talk and then write it down before I give one like it again.
Enthusiasm-- and a way to get it through to your audience-- is pretty important when giving the talk. I'm afraid I lack a lot of it compared to a few years ago. A few years ago, it was all new; now, though, long familiarity with the same ideas has reduced the story to something humdrum. I think I should teach the subject of black holes in a classroom setting to give myself some feedback, and maybe regain my enthusiasm. the April-May school break should give me a chance to get it all back, and maybe find something to work on.