I've been watching too many 80's cartoons this week, so I just had to draw some Rainbow Brite. Even though I used ref (which I can shrink down and post if need be), I'm sure there are some anatomy issues to be worked out before I proceed with the saccharine colors. Thanks in advance; I definitely appreciate it :)
it's not so much that the anatomy needs fixing, it's just that you are missing the subtle relationships of form and line that give the female form its oomph (and I don't mean big you know whats). Don't worry, drawing attractive human figures is a very difficult skill which takes years to master but you seem to be doing alright.
That looks pretty good. The proportions look right.
You might do well to remember that the pelvis and ribcage are basically boxes, and that a standing figure's weight is (almost) always on one leg or the other. The hip that the weight is on shifts up, and the ribcage tilts in the opposite direction to compensate. You've got the ribcage more or less right but a bit uncertain on the pelvis. Even if you're working from a photo, you'll want to exaggerate the gesture a bit to get the pose across.
Maquette render below, if you want to compare and contrast wth your drawing. If you're serious about learning this stuff, you might want to take a class in fashion sketching, which addresses these topics more directly than traditional art classes do.
I personally feel that her rib cage is a bit too large and her hips too small. Even if a girl has not so prominent hips, she still has a different pelvis than a boy. Her arm also looks disjointed.
On a side note, smile lines are not the best way to express breasts under clothing, it make it look like she has no bra on. Either shade underneath them, or just put a line or two showing that fabric is stretching over.
I came back to this hoping to finish it up. I feel like I lost any sense of "happy young girl" when I started working on the face, though, so any thoughts on that or the piece in general would be greatly appreciated.