Personalize it - don't just tell the story and then give all the implications. Instead, tell them what the coming of Jesus means to you today in your life.
It should be a natural conversation given the context of the person you're talking to. Often what we do is tell the story and how a person can find God, without ever sharing it's impact on our lives. Frankly, what I've learned is people are far more impacted by how it is affecting us personally and making a difference in our lives than all the "technicalities" of what and how. How has Jesus coming into the world made you different?
People are not waiting for sermonettes but want to know what it is that makes you different - once they see that, they want to know why and how.