Use a relaxed grip on the pick for the sweetest tone. These two photos show the ideal way to hold the pick.
The sound of the mandolin gets sharper and more aggressive the closer your pick is to bridge when you play the string. Experiment with the sounds you instrument makes when you play at different places on the string. It’s warmest when you play over the fingerboard and sharpest when you play next to the bridge. All of the voices of the mandolin are part of the musical range of the instrument. Learn to play at the fingerboard and EVEN over the fingerboard for a rich, elegant tone and close to bridge for a contrasting, aggressive voice.
Next, you’ll be amazed at the difference in the sound the mandolin makes when your pick lies flat or nearly flat on the strings as you play each note. This technique works best with a very relaxed thumb and takes a while to develop. To start practice playing gliding your pick over the G-string and letting your pick rest on the D-string. Then glide over the D-string; resting on the A-string. Then glide over the A-string and rest your pick on the E-string. Ignore the E-string for now, there’s no string for your pick to rest on.
When you combine playing over the fingerboard with this glide stroke the mandolin rewards you with a rich, harp-like resonance. Combine playing near the bridge with a tightly held, vertical pick for an aggressive banjo voice.
The Chromatic Glides Exercise is a really powerful for developing warm tone AND building the strength of all four fingers on the left hand.