Just checked in on your thread. You already did some nice progress ! Some small things to fix and you’re gonna have a great model !
About the hands, most of it you know already. Fingers look too thin for the overal size of the handpalm, and thumb needs restructuring. Just take a look at your own hands en make an expressive kinda claw-hand so you can clearly see where muscles and tendons go. Most of the time I find hands to be too smoothed an rounded, square-formed and edgy works better for me.
Knees might get a little more detial and extra edge, don’t know if he’s gonna get long pants
His ear should be a little more towards the back of his head as it is located just behind the end of the jaw.
In general feet to crotch = crotch to top, but you fixed that already.
Some little tips imo, hope they can help you to improve your model