Every speech needs to start with two things: 1) a WOW factor, and 2) the conclusion. The WOW factor can be an anecdote, an analogy or a story that is relevant to the topic and that hooks your audience into paying attention. Once you’ve got the audience’s attention you can reveal your conclusion.
Sometimes the WOW factor is the conclusion. Take for instance the first 22 seconds of Obama’s “The US killed bin Laden” speech.
WOW factor and conclusion combined: a very powerful opening.