Haha I'll cover the whole shading hair and clothes thing. Deb is right, the shading on the hair looks pretty dirty. This is because you've been pretty much using black to shade the hair. That's probably the most evident in the first picture.
That's a really bad habit, don't get into it. Never ever shade with black unless something actually isss black. Then it could maybe be okay. I did notice an improvement in that throughout the pictures though. The color choice for the shading in the hair got better. But you do have some room to be a little bit more daring and diverse with color choice. When you're adding highlights to the red hair, for example, try not to use that really washed out pink. Use yellow or orange or something more vibrant. Same goes for even the pink hair you drew. The hair is pink and saturated, don't make the highlights that really washed out unsaturated pink color.
On another note, on the last picture that's colored on your original post, you used a pinky color to shade the face, and that's AWESOME <3 You never wanna use blackish type shades to shade skin either.
As for the clothes, clothes never conform to the body like that unless it's like one of those latex or spandex full body suit things. And even in that case, there areee folds.
Clothes fall into folds when on the body. Look at references on deviantart or even on google images to see how clothes react and fall when on the body and when in different positions. Here is a super good tutorial/reference when it comes to clothing and folds and such
http://www.deviantart.com/art/Tutorial-Clothing-Folds-1-176116285
study that. Make that your bible.
Clothing pretty much alwaysss always always has some kinda folds somewhere, no matter how tight or whatever. Always.
Other than that, like Deb said, the face variation is really good, and you have so much potential and have improved a lot!!
So that's it
![Big grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Maybe later i'll drop off some color palettes that show you base colors and what kinda colors you could use to shade and highlight and stuff like that, if you want. Just so you can see
Anyway, keep on drawing <3