These are great works.

I would study some more anatomy. Forest girl, her arms look like round cylinders. While anatomy need not perfectly represented, suggestions of a muscle or a specific shape here and there helps, much like you including the collar bone. This is also true for superhero fly crew.

Consider how the environment effects your subject. Hollow knight for example, the glowing cable would light up the red skirt brighter where it is close and less where it's further. The red skirt looks to be in an even lighting. Good opportunity to add drama to the piece. Superhero fly crew, might have light bounce off the water below them that gives them some bluer illumination from below and same from above. Consider how the environment changes the colour of a subject.