My thumb is pointing to the left about 45 degrees. I just place my relaxed hand upon the neck and that's the position my thumb is already in. Having it pointing up would seem to cause unnecessary strain on my hand.

And when moving up to the higher frets, my concern doesn't have to do with keeping the thumb behind the first finger but more to do with keeping the thumb pointing up (which is already hard to do in the first place) because of the heel sticking out in the back and causing you to have to stretch your fingers to the 24th fret, resulting in a thumb that is almost pointing directly to the side.

Here's a link to a picture of my thumb on the neck: http://img85.imageshack.us/img85/971/thumbpositioningonguitaek7.jpg

^ Hm...I guess my thumb actually does point mostly upward in normal conditions. But because I sit in classical position the neck is angled about 45 degrees, causing my thumb to be at about a 45 degree angle from the neck.

Lol my roommate who is playing in the background has a thumb positioning that is hanging over the edge...the exact opposite of what I am going for here.
You should keep your thumb in the middle of the neck when practicing techniques or when shredding, but when you're playing bends and stuff your thumb should be somewhat over the neck. Just hold it the way its comfortable for you, there is no right or wrong, aslong as you don't hurt your hand you should be alright....
My advice as a ''technical'' guitarplayer, keep your thumb in the middle when practicing techniques !

Damn this is hard to explain in english Dx
S---R---D- SHRED

How many times do you see SHRED in this?
thats what i think. but i play the way ur naked friend plays.
Call me "Shot".

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