Not bad for your first time, I think it looks fairly good. You even put in the effort to add extra details to Haku's hair, and eyes. The rest of your coloring is decent, but I think you should learn how to make blood look more realistic. As for the background, it's plain, and simple, but it definitely works. Well, since I don't know a lot about coloring like this, I can't give you that much useful advice. However, based off what I see, I definitely think you have the potential to get good at this type of coloring.