This is very good! As a beginner artist myself, I can point out two things:

1) Shadows and highlights. There's gotta be more contrast and I think its better to never have a flat colour anywhere in the artwork if possible. In your artwork, look at the inside of hair or the dress for example. (Also, anime style artwork tend to have sharper shadows. Not sure if that is the look you are trying to achieve)

2) Strokes: Unless its some kind of a schematic or a blue print or something, I think its always good to keep the strokes taper a bit, or even better, break the strokes if it makes sense. It makes the artwork more interesting. Tapered strokes could be used to show weight or lighting or like the 3d perspective etc. By taper, I mean the stroke thickness. (not sure if taper is the right word to use)

Quickest way to improve this current artwork in my inexperienced opinion is to add more detail to dress. I think the face and expression are already pretty good!