If you're convinced that using humor is a good idea, but you're not sure how to do it, here are a few tips:
Don't feel you have to be a stand-up comedian to use humor effectively. Anyone wanting to be perceived as the next Bill Cosby will be frustrated. Come to appreciate your own style rather than comparing yourself to professional comedians.
Be adventurous and give humor a try. Try to add one new humorous story or example every time you speak.
Learning to use humor is not difficult, and it's one investment on which you'll always get a great return. Once you have an understanding of humor, you'll feel more comfortable using it.
Get your creative juices flowing by looking all around you for sources of humor. Politics, news, television shows, current movies, sports, best-selling books, the group you are speaking to, and even the people in it are all potential sources of topical humor.
Read books on humor—anthologies, collections of jokes for speakers, and so on. See what people before you have used in various situations. Almost every industry has some sort of humorous slant, inside jokes, and vocabulary. I once addressed an insurance group as the "people who knew how to fill out a 5500 C form"—something everyone present could relate to.
The better prepared you are, the more spontaneous you can be. The best way to learn how to come up with something funny on the spur of the moment is to learn how to do this before the moment occurs.
If you have a strong comic sense, that's great. But realize that if you can tell a simple story—and I've never met anyone who couldn't—you will get warm chuckles of empathy and recognition, which are just as encouraging for the speaker as laughter.