Many of us have found that after years of practice and commitment that something is still not quite right with our fretting hand. At certain points during our development as guitarists, it is important to reassess what is going on physically and potentially make some conscious adjustments.
Most teachers recommend an exercise regimen to address fretting hand problems, but exercises by themselves won't help you understand why you have problems with your fretting hand, nor will they help you pinpoint specific muscular inefficiencies within your hand that get in the way of fluid, accurate play. In fact, in my experience, exercises typically focus attention in the wrong place (getting through the exercises) instead of on pinpointing underlying problems.
In other words, in order to have a solid, agile fretting hand it is important to get comfortable with the way that the muscles in your hand work:
The muscles that close your fingers into a fist are called flexors.
The muscles that straighten your fingers are called extensors.
When you use the flexors and extensors at the same time, your muscles work against each other and unnecessary tension is the result.
The goal is to make sure that in as many cases as possible (there are always exceptions to a rule) only your flexors are used when fretting a note, and only your extensors are used when releasing a note.
The most common problems that cause both the flexors and extensors to be used at the same time are:
Holding unused fingers rigidly above specific frets because a teacher once told you to do this arbitrarily as a rule. Drop this rule and don't look back. It will only cause you problems. Looking ahead to what notes you will be playing and adjusting your hand and fingers accordingly is one thing, but holding your fingers in place just to hold them there makes no sense.
Not releasing with the flexors before using the extensors to lift a finger off the fretboard.
Putting your thumb in a position that causes tension in the rest of your hand. Your thumb will most likely be comfortable outside your fretting hand (try this without a guitar and see what I mean). The more you move your thumb towards your pinkie finger, the more tension you will build.
Not putting your hand in the most comfortable position for whichever finger happens to be fretting a note at the time. This can be over or under rotation at the elbow, tension in the wrist or shoulder, etc.
With this in mind, spend some time getting in touch with which muscles you're using when you fret notes. This should be done without a metronome and without trying to play any actual music. Just fret some notes using each of your fingers and start to monitor what's going on inside your left hand. You'll be amazed at what you can learn and how quickly you can improve just by becoming aware of the muscles you're using when you play. The important thing is to become more comfortable and reduce unnecessary tension.
Once you get comfortable with this you can start monitoring your left hand while playing passages within songs.
For a video version of this lesson please see www.whyisuckatguitar.com