Looks like a good start. There are some major issues on your cycles though.
Especially in walk and run it looks like she's stiffening up her knee's, almost like they're stilts. Also, in those two animations, the perspective of head, torso and hips are off, always tilted towards the camera while the motion is straight to the right.
The leg movement is.. interesting.
The walk seems like a locomotive engine, the run is like happily wading with straight legs through mud.
The sprint is actually pretty good. It just seems a bit stompy when the front foot comes down. Looks like it would absorb too much energy through the ground instead of boosting her up.
I'd suggest to make the animation frames locked-in-motion for testing how it would look. still animations can often deceive you, or rather, you can get more info if you're seeing it in motion, and if it would look properly ingame as well. Here's what i mean:
I like the subpixel animation on the torso in the idle. The arm movement is a bit weird though. i kinda get what you were trying to do, but try moving and bending your arm like that. movement of the shoulder also translates to elbow and wrist.
it is difficult to show in such low resolution sprites, so you might be better off with idle animations like tapping the foot, scratching the head, arranging the belt. stuff like that. normally idle people don't move all that much aside from actions like waving hands, changing poses/shifting weight, etc.
On the sprite itself:
Generally the upper legs seem disproportionally short which makes her look rather comical.
There's a weird mix of flat shading and details going on. compare shirt to trousers to head. I'd either simplify shading on the shirt, or advance it slightly on the other parts to get it more unified.
overall the sprite has a very brown palette:
Here's a suggestion for a more colorful version
This forum is a good sample why working in largely the same hues is a bad idea. she almost vanishes on that background. Keep in mind to maintain a good readability on different backgrounds if possible.
Hope this helps!