Avoiding the Left-Hand Death Grip
When you first start playing, straight away you’ll discover that pressing the strings against the fret board how-to-play-the-guitar is hard work, hurts your fingers and makes your wrist ache. The natural way to combat this is by hooking your thumb over the top of the fret board to get leverage, which inadvertently causes you to press the strings more with the flat pad of your finger (where your fingerprint is) rather than the actual fingertip.
This is sometimes called the “death grip”, because you do end up with a fairly fierce grip on your neck and it restricts the reach of your fingers. The proper technique is to have your thumb on the back of the guitar’s neck. This forces your hand to use the fingertips, which is far better and more accurate when it comes to playing just the notes you want without accidentally muting adjacent strings. The trouble is — it feels kind of weird and difficult at first, and your wrist will lack strength. Stick with it and you’ll appreciate the benefits further down the track. Remember, thumb on the back of the neck.