The final step to preaching a sermon that effectively tells a story is to Practice.
Record yourself telling the story. Then transcribe the story from the tape into a manuscript. This practice will improve your storytelling and your preaching in general.
It is amazing to me how often we preachers will not practice our craft. The musician practices for hours before she comes and performs. If the musician can practice like that to provide an enjoyable experience for the listeners, how much more should we, who are delegated the responsibility of proclaiming the greatest story ever told, practice the messages God gives us to preach.