A Mormon Times article entitled, "Five tips for a better sacrament meeting talk" yields the following:
1. Do not begin a talk with the story of receiving the assignment,
2. Do not spend too much time introducing yourself.
3. There is no need to justify the topic.
4. Use humor sparingly, if at all.
5. Teach something, don't just speak on a subject.
I find his five recommendations helpful. As much as I enjoy humor it has its limitations in Church. It can be "intoxicating" for the speaker if the congregation laughs at his/her stories. Here is some guidance from "Teaching, No Greater Call: A Resource Guide for Gospel Teaching."
Use light humor. With a lighthearted touch, you may be able to turn the person back to the lesson. However, you should never be sarcastic or use humor to embarrass or control.
Avoid sarcasm and demeaning humor.
Introductions to lessons should do more than get learners’ attention. If an introduction does not relate to the lesson, it will probably detract more than help. For example, if a Sunday School teacher tells a joke at the beginning of a lesson, the class members may become attentive, but they also may be led to think about things that will keep them from focusing on the principles to be taught.The reason most humor is used at the beginning of a talk or lesson is generally because it grabs the audiences attention. However, the quote above points out that if grabbing the audience's attention does not directly relate to the lesson it "will probably detract more than help." As the Mormon Times article points out, "it's sacrament meeting, not stand-up comedy."
With humor, let's be careful out there . . .