Fingers

Okay but: fingers are slanted or
angled and not perpendicular to the
fretboard. Could cause for buzzing
strings or misfretting.

Better: fingers are rounded and tips
are close to are at perpendicular to the fretboard.

Wrist

No good: wrist is hyper extended or
twisted.

Good: wrist is slightly arched and
perpendicular to the forearm. Look at the picture below left also

Elbow

No good: too close to the body, using this joint to move up and down the fretboard. Creates pressure on the wrist.

Good: elbow is used to move
vertically up and down the strings and
not horizontally.

Shoulder

No good: shoulder dips to
accommodate the neck position, causes misalignment of the spine

Good: shoulder rotates the arm up
and down and is used to move the armup and down the neck of the guitar,adjusts the neck as needed