When it comes to learning and genuinely retaining something, nothing beats experiences. Formal educational or speaking settings don't always allow for actual hands-on experience with the content, but almost every learning situation — including presentation in various forms — does permit the use of stories. Stories, that is, that illustrate the content and bring people in, enabling them to "experience" the material in an engaging, visual, and imaginative way. A way that will be remembered. One can use analogy, or metaphor, or the depiction or verbal reenactment of actual, relevant events that illuminate and make the material more real and more memorable. Stories have an emotional component and when you engage people's emotions, even just a little bit, you stand a better chance of them paying attention and remembering your point (whether or not they agree with you is another matter entirely).
Good advice from one of the best speaking blogs. Click through for more detail and for a link to a podcast with astrophysicist Neil deGrasse Tyson, who "touches on the issue of experience and emotion and the importance of enthusiasm."