I think one thing that can really add interest to a piece is a background, even a blurred one, because then you have things like bounce lighting to take into consideration. When you have just a plain solid background, there's nothing that's giving the storytelling elements, like @pifalo mentioned in their comment. You also may be dealing with some "flatness" when it comes to your shading and values. Have you tried looking at the image in black and white? This is very helpful for seeing a value map of the piece.
Matako
Notas do artista:
Generally speaking im feeling that artwork looks too “amateur” or rather “uninteresting”. My main dissatisfying with this drawing is that i dont know why someone should care about it when they see it, it kinda unappealing for some reason and i dont know why (and same thing happens with my other artworks) the only things i can think of are face/hair, rendering and colour, yet it still feels that i have more global problem so im confused with what the main thing that needs to be fixed
Comenta 2
Try to tell a story with your image. You can do that by adding an interesting background that can help tell us why we should be interested. Your drawing is nice and has nice gesture, so just think about a cool background other than her just sitting on a box.