Immediately I noticed that her back curve is very sharp and makes a V shape. I think that you should make it almost like a slight elongated U shape. It is also positioned way too low on the far right. Also where her back dips on both sides one side is bigger than the other. For example the lower half of her body is disproportionate to her upper half. I like the way her hair flows smoothly from off of the bed too. I also notice that in the background there are what I think is the sun that is coming through shades? I think that you should soften the light and spread it out so it does not look like two lines but instead a ray of light. Speaking of light I think that you should brighten up the colors, I think that it will make the piece more eye catching! Keep working on proportions with lots of real life references, soften those edges, and make the colors bolder. Good job!