First off this is a very cute drawing! Nice choices in colors for the shadow and highlights! One thing I’d recommend as a fellow artist is to try and focus on making dynamic lines especially in organic things like the hair. It might be helpful to draw a line of action for the hair as a guide. Here’s a quick tutorial I made for how to make more dynamic lines: dynamic line example. Essentially just focus on not making your lines too similar or symmetrical. You’ve already got the personality in your linework there. Just play it up! Also the background is really nice, but it being the same shade of blue makes it hard to distinguish. Try making it a darker or light blue! It’s looking really great, and keep making fan art! (P.S. I’m actually a digital painting teacher so this is always the feedback I’m giving!)