you're faces are very good man!
i really like this last pose, though the lighting is not idea =\
I also believe her thy may be 10% too big.
keep pushing it, and expand the canvas so you can finish the head =D
Do not, ever, under any circumstances, not have fun.
nice work mate, heed what the guys are telling you. I don't need to add my bit, they're already giving you good advice. You show a lot of promise for your age. Practise practise practise, and post. Thanks.
when people say your image is muddy, it's most
likely you are painting in greyscale then converting
to color by adding over top. try to use a "Color Balance"
layer on your greyscale image to add color and not adding
it with a brush. then work with the image from there.
Maybe less of the low opacity on your brush, your work looks more confident and solid when there are more solid color strokes. It will also help you consider form and dimensionality more. Otherwise, kickass progress... draw more!
Cool stuff in here, oki I really like the clay sculpture you're working on, it seems to be coming along pretty well (I kinda like how the head is still a piece of foam - are you going to make the head on a separate stand and then put it on there or are you going to sculpt it directly on the figure?).
As for the drawings in here, it seems to me like you're not pushing them far enough. The bare bones are there, but then you quickly slap on some shading and call it done. Line confidence is also something you could work on, there's lots of scratchy lines rather than smooth flowing lines, which make them a bit weaker than they could be, since the proportions and anatomy seems pretty much alright to me. Just push those values!