1
Make sure your left hand fingers stay as close as possible to the fret-board, even when they’re not being used. Having unused fingers flapping about will slow you down by adding a lot of unnecessary effort to the process of playing
2
A left hand change of position needs to be anticipated so that it is smooth and seamless. A hesitation or missed note/s due to not being ready for the move will not sound good. So, if you’re playing down on the low frets and have to get to the 12th fret, focus on the higher fret just before you go there. If you’re looking at the destination fret before you move, you’re also less likely to over (or under) shoot!
3
A quick exercise for improving agility, strength and independent finger movement in the left hand. Next time you need to scrunch up a load of newspaper – maybe for making a fire or throwing at someone – use just the left hand to do the work.
4
Don’t grip the neck of the mandolin too tightly. This can happen if playing under pressure, when playing something difficult or fast, or maybe it’s just a bad habit that’s stuck. All it will achieve is slowing you down and taking the life out of the music.
Some grip is needed, of course. But just use what is necessary and no more. Keep everything relaxed
5
As with not gripping the neck too tight, you should also avoid applying more pressure than needed with the left hand fingers when fretting the strings.
Use the minimum required to get a good clear tone from the instrument.
If you have to use a lot of effort to get a reasonable sounding fretted note, it may be that the action on your mandolin is too high. That is the distance you have to press the string down to bring it into contact with the fret. If you’re unsure about this, it’s always worth getting an expert to take a look at the action.