So, don't do this:
AU: Good afternoon. My name is Alex Umlaut. I am from Olympus Mons University. My talk is titled non-isotropically depolarised orthophasic omicron graticules.
First, I will give this outline of my talk.
Then I will spend most of the talk on background material that you already know. There will be lots of detailed equations in a small typeface that I will flash on the screen, but I will tell you that you don’t need to read them. I will use lots of needless animations that will make you feel seasick.
When I get the five minute warning from the Chair, I will realise that I am running out of time, and will race over all the new and interesting parts, and completely skip 10 slides.
At the one minute warning, I will tell the Chair that I am on my last slide, but it will have 20 different reveals on it, and I will go well over time.
Finally, I will end with my conclusions. I will mumble off into silence, so that you will not be sure that my talk has actually finished.