To sound authentic when you play classical guitar, you must play it in the classical style. That means you have to follow the specific rules about how you hold the guitar, position your hands, and play your notes. Even if you have no intention of becoming a serious classical guitarist, you can improve your tone, technique, and phrasing by practicing classical techniques.
Classical guitar is always played on a nylon-string guitar and in a sitting position. Professional classical guitarists sit differently from other guitarists in that they hold the guitar on the left leg instead of on the right one. They also elevate the left leg about six inches by using a footstool. By holding the guitar in this position, you can accomplish the following goals:
By supporting the guitar entirely with your body, you leave your hands completely free to play. In this position, you rest the guitar’s treble side (the side closer to the higher-pitched strings) on the left leg, with the back of the instrument against your abdomen. The weight of your right arm on the bass side holds the instrument in place.
This guitar position enables the left hand to play any fret at the correct (perpendicular) angle. This allows you to play the higher positions (seventh and up) more easily than you can in the standard acoustic sitting position.
All that being said, the truth is that a lot of people who attempt classical guitar simply don’t bother with all this stuff about how to hold the instrument. Why? Because it’s too much trouble. Where would you even get a footstool? (Okay, you can get one at your local music store — maybe.) If you just want to try out a few classical-guitar pieces for the fun of it, hold the guitar as you normally do. The music police aren’t likely to arrest you, and you can still hear the beautiful arrangement of the notes, even if you’re not playing strictly “by the rules.”
However, if you’re really serious about learning classical guitar, buy a footstool and refer to the following figure to see the correct sitting position. Oh, and if you want to pursue classical guitar, learn to read music (if you can’t already); lots of printed classical guitar music comes without tablature.
Some people don't like to use the footstool because it creates an uneven pull on your leg and back muscles. If you would prefer, you can try using a special gizmo that pushes the guitar up from your leg, enabling you to keep both feet flat on the floor.
What’s important is that you keep the guitar in the proper position, which means sitting upright and at the edge of the chair, elevating your left leg (or the guitar), and holding the instrument at the center of your body. Keep the head of the guitar (where the tuning pegs connect) at about the same height as your shoulder.
Classical guitar is more than just a musical style. The way classical guitarist approach their instruments is quite different from that of any other style. Classical guitar encompasses a long tradition of techniques and practices that composers and performers have observed through the ages and to which they still adhere.
Just because it adheres to certain disciplines, classical music isn't all rigid rules and regulations. Many guitarists with careers in both the pop and classical fields have actually tried to infuse classical techniques into pop and rock playing, such as Steve Howe of Yes, Michael Hedges, and Chet Atkins.