It can be a little slow around here. ^_^;
What I notice about your art is that you have quite a good sense of anatomy and your faces look reaaally nice.
I think the main thing you could work on is smoothing out your lineart and a bit more CG practice.
The lineart is quite scratchy. I'm not sure what you use to make it... if you have a tablet, or scan in drawn art.
If you scan in your lineart, after doing it in pencil, go over it in a really fine pen. Just being careful with your pen is all it really takes to get smooth lineart. For example, I did this one in ballpoint pen only:
[x]If you do use a tablet, I guess it's just a matter of practice. n_n; Just keep going over your lines with the pen tool and erasing the scratchy parts.
CGing also takes a lot of practice, and I think you could work a bit on your shading.
Most of the skin shown in your pictures isn't really shaded at all, and the black items are shaded very sharply. Looking over some CG tutorials might help out. I think there are a few good ones posted in the Tutorials sticky.
Welcome to the guild, by the way. XD
[edit] I'll come back and comment on the first picture after school. xb