Humor can improve a speech better than anything else because it gets the audience to react positively to you. A joke will also help the audience remember a serious point you want to make. But this is the trickiest part of a speech, since everyone's taste is different and few speakers have mastered comic delivery. There are easy ways to lighten up a talk by borrowing the right jokes. You can also improve your own sense of humor with more effort and create some lines no one has heard before.