I wanted to give this a shot for some time since i'm a fan of unnecessarily long legs for female characters. (or generally disproportionate but still kind of working anatomy)
I think the lack of contrast in your piece is not just a matter of value (lightness) but also of color.
I'm no expert on the topic but as far as i understand it different hues at the same value (in HSV) can appear darker or brighter, so choosing a different color(hue) at the same lightness can increase your contrast as well. Combining those will create contrast not just in color but also brightness, or some-such. The theory is really weird for me, but i think i sort of start to get a feeling for it anyways.
Your skin currently is very light and flat, the shadow turns towards grey which doesn't make it feel very alive. Also the way you shaded creates only a sort of banding gradient towards the furthest distance from the light. it seems very generic and doesn't play with the forms of the anatomy or pose.
finally i felt it is really weird that the body seemingly faces straight forward (towards the viewer) while the head and the arms suggest an i'm going right motion.
I quite like the hair and upper body on your version tough I feel the skin has way to much contrast.. it almost looks as if she has some kind of skin rash?
its certainly given me some ideas..
as for lighting that's something I was trying to keep out of the character at this level.
this character has become a very early rough version / practice for a game project and our programmer wants to add dynamic lighting.
so i have been trying to draw the character without any directional light on them, that would probably be layered on top somehow.
i admit i have not really worked out the mechanics of it one of the reasons I am sharing and trying to get peoples opinions .
the pose is definitely wrong, when you strip away the baggy trousers the long leg shape has caused me some issues working out poses. id like to build her up as a sort of ,metroidvanian style sprite sheet, left and right movement of walking running jumping etc.
so i guess this pose better fits some sort of idle stand.
as i mentioned earlier in the post my experience in pixel art is quite limited and this kind of proportionate character is new to me.
I have been working on a level mock-up for a day or so to get a better feel for how the character should look and I am experiencing similar issues with colour and contrast there.
it seems my opinions on what looks right conflict with alot of peoples advice, maybe the style i'm aiming for does not fit the colour pallette.