Update: I'm not sure any of these are improvements but I figured I'd test out some ideas.
In this piece I added more contrast to the figure in the middle. I thought that may help to define her a bit more. The line art that I added around her clothes and around specific parts of her skin really helped define and crisp up the image, I feel.
I then noticed that she doesn't stand out well from the background so I experimented with lightening the entire background in this piece.
I then lightened her hair and skin a bit to give her more contrast herself. I don't think this last experiment helped much and seems to have washed out the image.