[Karin Wells]

Here are my suggestions.

I rotated the picture so that the eyes are parallel to the horizontal edge of the canvas. I think that this may make for a more interesting positioning on the canvas and eliminate the light/shadow division thet would go right down the center of the painting.

Have your background dark, simple and use a slight variation of value as an opportunity to lose and find edges of the face and figure.

A silhouette of a bow or ribbons on the back of the dress would be a good compositional device to make the negative space more dynamic. It would be a good opportunity to introduce a hint of another color plus maybe put a little touch of light on the dark side of the figure.

You can also make the space in front of the figure more interesting if you can paint her holding flowers. Oftentimes a touch of something darkish on the light side of the figure can enhance the overall look.

Leave plenty of "head room" in your painted portrait. It is only in photos that you can successfully get away with a close cropped figure.