The beginning sets the tone, so it’s extremely important to have a strong and engaging start. Much of it depends on your audience and the setting. Why were you asked to speak? What are their expectations? What is important for them to hear? Get as much information in advance about your audience and the structure and content will flow from there. Another technique is to ask your audience questions like “How many of you have experienced this?” or “How many of you are familiar with… ?”