The ability to place the left hand in a position to give equal opportunity for each and every finger to fret precisely is essential for playing well. Pinching a fret precisely means pinching a fret while avoiding contact with any adjacent string/s.

There are many instances where the ringing of adjacent strings is necessary.  Think of your Bach fugues!

So here are two exercises I like to show students who are struggling with placing left hand fingers precisely. Some things to keep in mind:

1. Listen! Keep your ear on the open string to make sure it rings continuously while you play the chromatic notes around it.
2. Play really slowly to insure absolute legato.
3. Keep right hand fingerings simple. Try using p and i or m for the open string.
4. Pay attention to your wrist placement. It should remain relatively flat. Do not push your wrist out in front of the guitar. To create a tunnel for the open string take the bend across the joints in the finger. Think of creating a semi-circle with the finger.

Exercise 1

Exercise 2

Hope this helps clean up those sloppy pinches! : )