Watch out for hairy lines. Especially on the quick ink gestures. A misplaced coinfident line is better than a un-coinfident line in the right place in most cases. Use fewer lines and make them longer.
The two first drawings with the jockey has a great sense of motion, I like that. Just a bit smple shading on the major parts, like the body of the horse and his helmet would have nailed it. The last horse looks like it is tripping forward.
Suggestions. Seems like you are struggling with some facial anatomy issues, specifically the placement of the eyes. I know that i've had some issues with this in the past. In my limited experiece, placing the forehead / brow as a three dimensional object, then nose, then lips, finally eyes has helped me a little. I would suggest maybe doing a long self portrait in pencil (seems like that's what you like) or charcoal and then upping the ante with trying to add in a full range of values. take your time, try to get everything drawn right, and then once you are comfortable with it, erase the extraneous sketch lines and start roughing in some value. These pages show some great progress, though it seems like the pupils might be giving you some guff. I usually avoid the pupils until i'm confident that i've placed the eyeball in roughly the right area. Try to think of the eye lids as flesh that wraps around the eyeballs, instead of the delineation between face and eye.