they look pretty good.
What kind of direction do you want to go?
At the moment the characters use a stiff posture that doesn't emphasize more of the characters form or shape, so it's hard to tell whether you want it stiff or if you're looking to express more shape/body to the characters. Maybe this is something to experiment with?.. looking at how to develop the volume of forms.

¿What do you mean with shape/body? (I'm sorry, english it's not my native language)
I drew the sprites in those postures because they were easier to draw. I want to use them for a game though, so I guess my new direction would be to try more dynamic postures to animate them, maybe doing a small walking animation? I can try to do one, but I'm worried about not being able to give the legs a good shape.