I need some tips on left hand position. I start with my thumb in middle of neck but my wrist feels uncomfortable. How do you position your wrist? Also as i play especially higher strings like D,a,E my thumb ends up at the top of the neck. Is thumb position real important?How do i get comfortable with my thumb and wrist position?
Thumb position is pretty important, especially if you want to play stretchy things with the left hand.

Can you post a couple of pictures of your hand? From a few different angles and while fretting a few different strings so we can see what might be wrong.
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