Samus Custom Sprite Sheet.

[BobbyLala]

@Alex IDV, Five stars is his/her alias rather than a rating of the sprites

As Alex IDV said, more contrast between the shades would be helpful

In the first pose on the sheet (top left) Samus is leaning back too far, bring forward her torso so that she's balanced
Could you animate the run cycle for everyone's convenience please? it's more difficult to critique them as static frames
I'm not exactly sure what the bottom-left sprites are, is she jumping or jump-kicking?? whatever she's doing, the legs look wrong as the far leg(our right) looks very short and awkwardly bent. I can't tell whether it's coming towards or away from the viewer because of the foot

with the shoot and jump(?), more frames to the animation would be good.
Anticipation frames ie. bending the legs in order to jump, getting into the shot pose etc
Action frames, there are slight pose changes when jumping, recoil when shooting etc
After-action, Landing after the jump: simply recovering or perhaps going into a roll. & Whatever happens after shooting etc

i'm sure you can find some references to help you


Before you even think about all that though...

The overall composition of Samus isn't too bad, but...
She doesn't really have hips

I can't see much because of the low contrast but, from the icon you've posted there isn't a consistent light source.