Boobs are weirdly pointy and saggy.
Shading on limbs makes the girl look bow legged, consider lightening up the thigh to the knee and darkening the calf to show forward tilt.
Faces look like blow up dolls. This can be difficult in pixel art. You'll see a lot of artists simply remove the mouth, cover it with a nose and a moustache (Mario), or make it a thin shade line, etc. A single dark pixel gives off a :O face vibe, can be useful, but not what you want for a base.
Pillow shading on limbs flattens them.
Constant relatively light outline does little to give shape.
Lone pixels on males chest look like noise rather than what I assume was intended to be shading for the pectoral muscles.
Consider a static light source. Most of the time with front facing sprites, light sources from above or slightly to the right/left are popular.
It's difficult to give too much more critique without more context. Ultimately the goal is to create something that you feel succeeds for your purposes, so it can help to analyze your work and mention what you feel you aren't understanding or getting from it when asking for critique. Hope that was helpful, and good luck!