another simple thing I’ve practised a lot recently is just playing grips, and moving between grips.
To be an effective accompanist you need to be able to play chords quickly and cleanly and this is pretty hard to do at first.
One thing I’ve practised is as follows:
1 F# _________________________
2 D# _________________________
3 G# _________________________
4 E _________________________
5 B ________5__5__5___5__5___
6 G# ___________5__5b_____5___
7 F# ________5_________5______
8 E ________5__5__5___5__5___
9 D _________________________
10 B _________________________
I find these positions difficult to move between. I dont find the 8, 7, 5 grip that hard or the 8, 6, 5 grip. But playing them one after the other took some practice.
I think practising this generally helped minimise hand and finger movement, which seems to be the holy grail in terms of PSG technique (just my observation).
Players like David Hartley make what they do look easy because there is no surplus movement to their technique.
They keep their hands pretty still (which helps maintain a reference to where the strings are), and they
pick with a firm finger stroke that does only what it needs to. This means the finger has less distance to travel to get back into position, and that it is less likely to hit another string.
Apparently using the joint in the middle of your finger to perform the pick is the key to developing this minimal technique.
This takes practice..