A fine player and teacher in the classical guitar realm. He has developed a technique of using the little finger of the right hand, which is not only difficult in itself, but is highly radical in the classical world. He has published instructional materials detailing this technique.

Even if you are not a classical player, this technique is a good one to work on. At the same time, you can take a bigger lesson from Charles by breaking out of what's accepted to try something different.