A little humor can help lighten a heavy technical talk and prevent your audience from drifting off. But overdoing the humor can ruin an otherwise fine presentation and erode the speaker's credibility. Do not use off-color humor at any time, because what is funny to one person is offensive to another. Never lead off with a prepared joke. If it fails, it turns off the audience, and you look like a clown.
Good speakers supplement their own knowledge and experience with outside research and examples.
Interviews, informal chats, and letters exchanged with colleagues and experts in the field can further add to this information. Gather about twice as much material as you need. Then, when drawing on these data, you can be choosy, selecting only the best stuff. The process of doing research will also act to permanently increase your own knowledge. And this is a real confidence-builder to the speaker.