To deliver an effective presentation, a professional speaker must understand their topic and but they should also understand some basic information about the people in their audience.
1. People learn best in 20-minute chunks.
2, Multiple sensory channels compete.
3. What you say is only one part of your presentation.
4. If you want people to act, you have to call them to action.
5. People imitate your emotions and feel your feelings.
More information about giving a powerful and persuasive presentation can be found in 100 Things Every Presenter Needs to Know About People.