Now, take a picture!
Now that you've set up your camera, it's time for some action. There are two kinds of action shots. The more common type, frequently seen in sports photography, uses the highest shutter speed available to freeze the action. If the shutter speed isn't quite high enough, the subject might be a little blurry — which can look creative and cool sometimes, too.
Alternatively, you can go for a slower shutter speed and let the picture tell the story for you: Nothing says "This girl was really fast!" like some motion blur.