other than the ear and the whiter line on the back of the neck, your values are looking pretty good for the block in.
however if you can focus on getting your shapes mapped in more accurately I think you will see a big jump in quality. Here is what I said earlier about shapes... nice start btw...
When you are first getting started it is very important to really focus in on the mapping out of your shapes as accurately as you can possibly get them. If you put a shape in the wrong place and commit you end up having the other shapes off and require fixing, which increases painting time. By taking just a few extra minutes early on to measure out your shapes, to compare your shapes, and be sure they are placed and drawn accurately will make the rest of the painting process, working out your values and edges, much much easier.
Keep up the good work.
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