I couldn't agree with Segovia more when he said "study music more than the guitar". In that vein, I've been notified that there will be an online music theory course for guitarists at the www.classicalguitarblog.net
As I've said, to play classical guitar well you must also understand classical music. This course is specifically designed for classical guitarists and is interactive - you can ask questions and get answers about the material much like a "real" class. If you don't know theory and are interested, this can be an excellent course to get you started.