Hours upon hours of after-dinner speeches have begun with a joke, to -- ostensibly -- wake up a dozing audience. But don't you try it, advises speech consultant Sandy Linver, unless you're very good at it.

"Use humor," she writes in her book "Speak Easy," "only if it is original, you handle it well, and it is relevant to your subject. Leave professional entertainment to the experts."

The purpose of a speech, she says, "is to make something happen, and it is worthless unless it moves the audience in some way." Most speeches are either "informative or persuasive or some combination of the two." s

Her advice for preparation of a speech:

First try to express the idea of your speech in two or three sentences. If you can't, "your idea is too fuzzy."

Structure details around a few clearly stated big ideas. Then, "the organization of the whole speech will fall into place."

"Be specific, concrete and visual. Illustrate a general idea with a specific, human example."

Don't accept a speaking engagement, she warns, "if you can't immediately rough out a general idea of what you want to say -- or if you think you will spend more than half your preparation time researching the subject."