The first warmup suggested for pitching is the whip flip. Here is a video of my daughter with the wonderfully pleasant and knowledgable Rick Pauly.
<iframe width="560" height="315" src="https://www.youtube.com/embed/JnqM-7kZR8c" frameborder="0" allowfullscreen></iframe>
<iframe width="560" height="315" src="https://www.youtube.com/embed/JnqM-7kZR8c" frameborder="0" allowfullscreen></iframe>