I think a useful metaphor for beginning a speech is the handshake. Most audiences are friendly and open and will reach out their hand with good will. It's the speaker's job to grasp that offered hand firmly and shake it -- with the action and motion symbolizing the act of engaging the listener's interest.

The surest guide in creating effective openings is the same principle underlying the making of an effective speech: knowing the audience and occasion. Practice total immersion in the audience - even if you have only sketchy information and limited time before the presentation -- learn everything you can about the audience, location, and occasion. Interview your host; if possible talk with people who will be attending the presentation. Really try to get inside them, try to adopt the listener's point of view.

The more time you spend in careful thinking about the audience the more time you will save and the easier it will be to chose the right content, and more to the point, to dismiss almost automatically anything that doesn't fit. Is humor appropriate? If you know your audience you don't need to ask. Can you jump right in with the topic? In some cases where the audience knows you, where they know the topic, the point of view - it's entirely appropriate - but again, you've got to think about your audience and know your audience.

One important outcome of careful thinking about the audience is the almost automatic personalization of what is said. It makes sense because the more you feel you know someone the more open and relaxed you feel towards them and it's natural to be more personal and conversational.