This tutorial suggests a few exercises that you do prior to a speaking event. It highlights the importance of stretching the muscles in your face and how to warm-up your voice to properly articulate.
Video Length: 2:07
This video highlights what NOT to do with your hands and the proper way to look composed when you are speaking.
Video Length: 1:20
This is a quick resource that shows how you produce sound by using your organs of speech.
Video Length: 0:53