Untitled

I think the top left ones are the most solid. The eyes sit well in the face and the headshapes are good. Consider trying to use longer uninterrupted lines by lightly sketching the larger forms of the head first, and going over with bolder more confident lines. Add the little bumps and squiggles as finishing toches.
Also I would indicate the lips more than outlining the whole thing. This makes them less cougar-like xD The brain can often fill in the blanks of what is NOT drawn, cuz we're so used to seeing/reading faces. Kind of like this (not my drawings btw):

Your drawings show promise. Keep at it!

Nice job on your faces, SINE. Why don't you do another 1 hour class of your faces and expressions, please?? That way, your renderings of them will be more and more confident, yet careful.

Polyvios Animations

You've got a great start, especially for a beginner! (Trust me, I'm an art teacher.). Don't forget that the skull is the main form to look at, so try sketching that underneath first, then use that to line up the features of the face. You're doing great, keep at it!

rendering is not the best place to start! you should practice gestures first so you can figure out what a head/body/thing is, the shapes its comprised of, then rendering just kinda comes naturally!

I really enjoy your expressions of your faces. Good job!!