I was fortunate enough to have a great teacher who taught only fiddle, but was very keen on Kato Havas' methods, which is all about how you feel when playing, and how to minimise tension and maximise balance (http://www.katohavas.com/). Havas' approach was applied to classical music, but works for *anything* (instrument or genre) really. Unfortunately for me (but great for her), my fiddle teacher moved to Ireland in the summer, so I have a bit of a trek for lessons.