Here’s a few tidbits from an old article that seems to have vanished from the internet, called “How to Fail at Learning the Guitar”:
“If you’re just starting out on the guitar, it’s important to find one that’s either really cheap or really flashy.”
“Cultivate poor posture techniques early on, so that they become a learned behavior.”
“Start playing the guitar really fast before you’ve learned how to fret and change chords properly.”
“Give up when your fingers start to hurt.”
“Assume that you can learn how to play the guitar without anybody’s help.”
“When you discover that changing chords is too hard and that a couple of week’s worth of time investment hasn’t made you sound like Clapton, make sure to give up immediately and never touch the guitar again.”
Assuming you can learn how to play the guitar without help should be close to the heart of anyone who wants to learn to play for free, but the author of this article, Jonathan Dewbre, who does not appear to be a guitar teacher has hit the nail on the head on many points.
Increasing the speed and accuracy of your guitar playing is not possible if your body is tense. Learning to play guitar is not just a matter of spending time hunched over an instrument. You will need to pay attention to HOW you play.
If you are not used to working with the tensions in your body, a good start would be to simply stop what you are doing and check for any tension anywhere. You could use the timer on your phone or computer to remind you, say, at fifteen minute intervals, just to ask yourself where you are feeling tension.
If you feel that there is a buildup of tension in any area of your body, simply try to adjust your posture, rather than trying to eliminate the tension by letting your arms go limp, or some similar technique. If you like, you could try shaking and stretching to get the tension out.
By adjusting your posture I mean making sure your body is not twisted, your back is straight. Keeping your back straight is a matter of pivoting your upper body on the bones of your butt until you feel your back is straight without being tense. If you find you are continually assuming a slumped posture, try using cushions to make your pelvis lean forward slightly so your back is straight.
Here is a video detailing the advantages of maintaining good posture:
Of course, you will need to work on your posture in conjunction with your guitar. There are a lot of factors at work here: how you hold the instrument when you are sitting; do you need to adjust your position so you don’t crouch or slump; if you play standing up, is your strap so low that the guitar is difficult to reach.
You could stretch your neck, shoulders and back before you begin your guitar practice and again when your time is up.
Adjusting the posture of the whole body is not always necessary. Here is a video by bassist Gary Willis on paying attention to finger pressure as you practice.
If you are having difficulties with pain or tension due to guitar playing, keep a limit on your practice time. Many guitar players would love to organize their lives so they could practice for three, four or six hours a day, but if your body doesn’t like the idea, then stick to one or two hours.
Here is a link to a couple of videos by guitarist and teacher, Justin Rothberg showing how to use both left and right hand for guitar playing.