Oh! Now that you point that out I can see that they are blue but here is my suggestion (you dont have to use it)is to make the color in the eyes bigger (not the eyes themselves they are beautiful)because you probably used zoom to complete them, and we viewers dont have zoom and if we did we wouldn't focus on the eyes, so maybe a bit more color other than that. LOVE the drawing! Good Work! <33
Most of the time I use a tablet. But if I go somewhere where I'll be for a long time I have copic markers that I bring with me. I used to use prismacolors too and very once in a while I'll use watercolor pencils. I just don't use the other mediums often because I don't leave the house much.