You've heard me mentioned that the best stories are personal to you, but they don't have to be personal. But if you're not going to use personal stories, at least tell an old story that maybe people have heard before, but do it in a new way. There's got to be a new lesson there a new twist. Malcolm Gladwell, The New Yorker writer and best selling author does this so well. With his speech on David and Goliath. He talks about an old story people have heard of for thousands of years, but he tells it in a completely different way with different lessons.
That's what makes it so effective.