One of the simplest techniques that gets overlooked in the left
hand is the finger-per-fret concept. When we place our left hand
on the bass, it is important that we assign one finger to one
fret, four frets across.
The fingers are placed just behind the fret to obtain the best
sound. The further you move the tip of your finger into the
middle of the fret, the more buzzy, noisy, and thin the sound
gets.