Speed & agility are without a doubt two very important factors in athletic performance. Training for speed, quickness, and agility can be done in many different ways and many different progressions. Therefore the question is: What exercises are best to improve these components? And how do I progress these exercises?
In this post by Todd Durkin, CSCS, those questions is answered. First, Todd breaks down the two most important factors to improve speed: stride length and stride frequency. He goes on to give some examples of dynamic warmup exercises as well as flexibility exercises. In the rest of the article, Todd explains speed by breaking it down into parts and phases for tips and exercises for each. He also gives a nice progression of plyometric exercises.
Its a lengthy article due to all the lists but at the end you can download the article as a PDF which is convenient. Check it out to add to your toolbox!