Whether you sit or stand while playing the guitar won't affect your tone or technique. What can make a difference is if you're not holding the guitar properly. Most people prefer to practice while sitting but perform publicly while standing. If you know how to properly hold the guitar while sitting, you'll be able to pick up the techniques more quickly because you'll be more comfortable.
Although you can usually choose to either sit or stand while performing, the one exception is classical guitar, which is normally played in a sitting position even in public performances. That doesn't mean that you can't practice or play a classical-style guitar while standing, but you do need to learn how to play seated if you want to seriously pursue classical guitar.
Holding the guitar while sitting
To hold the guitar in a sitting position, rest the waist of the guitar on your right leg. (The waist is the indented part between the guitar’s upper and lower bouts, which are the protruding curved parts that look like shoulders and hips.) Place your feet slightly apart. Balance the guitar by lightly resting your right forearm on the bass bout, as shown in the following figure.
Don’t use the left hand to support the neck. You should be able to take your left hand completely off the fretboard without the guitar dipping toward the floor.
Holding the guitar while standing
To stand and play the guitar, the first thing you need is a strap that is securely fastened to both strap pins on the guitar (or otherwise tied to the guitar). Then you can stand in a normal way. You may need to adjust the strap to get the guitar at a comfortable playing height.
If your strap slips off a pin while you’re playing in a standing position, you only have about a fifty-fifty chance of catching your guitar before it hits the floor (and that’s if you’re quick and experienced with slipping guitars). Don’t risk damaging your guitar by using a strap that is worn or that has holes that are too large for the pins. Remember, guitars aren’t built to bounce, as Pete Townshend has demonstrated so many times.
Your body makes a natural adjustment in going from a sitting to a standing position. You should strum the strings of a guitar between your belt buckle and your belly button. So don’t try to overanalyze where your arms fall, relative to your sitting position. The following figure shows a typical standing position.
