Rehearse. And rehearse again.
In the end, a great presentation will come down to the speaker’s ability to capture the audience’s imagination—and keep their attention. The presentation and the speaker should work together, meaning the slides should complement the speaker, and the speaker should complement the slides. The best presenters won’t have to look down at notes, and they’ll never be reading from a script. Focus on the key points, and let handouts or packets outline the minutia. A good speaker can convey information well; a great speaker will sell an idea.