I am a beginner, never played bass before.
I noticed my left hand is going out of control during practice. My thumb keeps changing position, and the more I play, the more it is tensed. I even have aches after trying to maintain some positions.
The more I play, the more my hand looks like a claw and I cannot keep up even simple positions (I am in module 4).
It is probably because I have a bad position and because I am stiff as a stick.
And that damned pinky is not doing whatever I order it to do
Any advices on trying to be more stable with the thumb ?