also, i would love to know what DOES look good. if there is anything, of course.
Just so you know, this community is mostly about helping and improving, so usually people don't comment on what is already fine, and can't be improved. Lack of comments about something *never* means it is without merits, it's the opposite.
But since you're unsure, I can say you did an impressive job on the first one's curls and the vest's opening. On the second one, your usage of a single-pixel-wide line to emphasize the separation of two dark parts of the hair is also something that few people attempt, as it's difficult to get right - and you did there.
Note that on this forum, you can click and shift-click all embedded images to change zoom level.
I suppose you received critics of "pillow shading" and don't really see how to take them into account, so I'll try to give specific help about it : The general rule is that surfaces that are facing the light source should appear lighter than surfaces at a sharp angle (or away from it).
The difference should be made very strong on reflective materials like chrome and latex, but much reduced on materials like cloth or fur that scatter light.
For your characters, hair should convey lighting a lot, skin much less so, and clothes nearly not.
For a character sporting a fringe, I would first start with a big bean-shaped highlight over the (hidden) forehead.
I'm thinking of a shape like the central highlight on this apple :
http://www.drawinghowtodraw.com/stepbystepdrawinglessons/wp-content/uploads/2011/09/step-106.pngIt's visible even on an actual photograph of a real-life person (it gets cut where the fringe parts, and resumes on the other side) :
http://cache.cosmopolitan.fr/data/photo/w1000_c17/4h/frange-longue.jpgActually I made an edit to illustrate:
In each color range, I mostly reserved the lightest for the highlighted part.
I simplified the hair to focus on how it catches light.
The buns are an excellent opportunity to shade them as if they were spheres.
Lower part of arms darker than upper parts (recessed)
Highlights on shoulders (2x2 pixel)
Higlights on lower thigh/knee (2x3 pixel), contrasting with the lower leg.
Note that convex shapes work best as highlights, and at extremely small pixel sizes you can fall back on squares/rectangles, in the viewer's eye it will still be perceived as an ellipsoid.
The following changes are more experimental, I'm not sure if I did more good than harm :
Highlighting the cheeks rather than the eye-level. I'm really not sure it's a better result (or approach), as I'm really not used to drawing chibis, or even anime in general. The lesson here is that it's very hard drawing something if you don't know its actual 3D volume.
I amplified the bosom to show how it can be shaded : upper half lighter (if it wasn't already very light), lower half darker. It conveys how the upper half is facing the light, and the lower half is facing away from it. It's not the same thing as cast shadow.
I thinned the dark separation of jaw, because I felt it didn't need to be so thick and emphasized..