*Deji butting in outof procrastination*
Your girls look cute ^o^!!
I specially like the little one =P
Now, me being me, Iwent and did a resketch and recolor of your sprites to explain a couple of things to you that were bothering me.
Of course this is just an advice, so you can take whatever you think it helps you and discard whatever you think it's not useful to you/you don't like ^^
Ok, a couple of things anatomy-wise:
The heads of both girls aren't centered in relation to their necks/bodies, both heads are placed a bit to the left.
The top of the head looks too pointy, imo... it reminds me a bit of an egg X_x; flattening and softening the curve looks beter for me.
Now about the coloring, I have a problem with your gradients... not because they're gradiends, but because they come from diferent angles Dx; In the grown-up girl, the skin is lighter at the right and darker at the left, but the hair and shirt are totally the opposite. It's confusing! So keep them all coming from the same part of the screen.
The hard, cel-shaded shadow on the chest of the grown-up girl looks nice (I like soifter shadows myself, thou), and I think you should add a bit more of those on the rest of te picture, like in the hair and skin, for example.
------------------
musical74 was discussing about the highlighted part of the hair.
It's an issue to a lot of people, really, but it's not as complicated as it seems. Well, I mean you can always simplify it if it's giving you troubles =3
The first one is the easiest and simplest thing ever xD;
The second one is a bit more like a alo, but it's wider on the direction the light is supposed to come from and it gets thines to the opposite direction.
The third one is the same halo, but he bottom was erased with a big soft airbrush-y brush.
The fourth one is a bit more tricky. The idea is to make lines, inside the edges of the hair strands that are on the side where the light comes from (in this case, the right). On the thicker strands, you can draw long agled lined to form VVV shapes. To soften the lines you can erase the tips with a soft airbrush-y brush.
Fifth one is the same than fourth, but I also used a big soft airbrush-y brush at low opacity to go over the highlights.
And the last one is the fourth one plus dodge tool, using a soft airbrush-y brush again XP
Hope it helps!
(btw, if I'm being annoying, please let me know and I'll refrain myself from resketching your stuff from now on DX;)
everything seems nicely done and I like the sprites 
