Finally, humor. Don’t leave it out. In the world of paid professional speakers the answer to the question, “Should I include humor in my talk?” is, “Only if you want to get paid.”
On the other hand don’t decide, as a kind of after-thought, to stick in a little humor when the preparation is all but finished. For example, you show your own emotional immaturity when you tell a joke that almost fits, but not quite. Neither you nor your audience may even be aware of it, but you will have inadvertently let the air out of your own tire, and the sense of authority you absolutely require will start to leak out, never to be recalled.
So what do you do? Well, as is the case with all humor, it’s hiding in plain sight all around us. Part of the fun of preparing a speech, like part of the fun of life itself, is uncovering the humor and sparking it into life. So also here: uncover the humor that’s already there.
Where, exactly? That’s for you to discover, right? And when you do the grunt work this implies you’ll be just like that concert pianist applauded before he’s played a note – who then justifies that applause by going on to play flawlessly!