1. Speak loud enough
2. Speak clearly
3. Look up at the audience when you are speaking.
4. Stay still, try not to fidget.
5. Don't speak to fast, and include pauses.
I'm going to add one more to that list:
6. Speak with expression
Here are the videos. They are in a playlist, so you have to search through the playlist to find yours. You can click the button in the top left corner to easily find yours.
1st Practice
2nd Practice