Hey there! Eewee and I ended up doing something very similar. I just copied the blue rim light because I liked it, hehe. But something else you could consider is cleaning up your drawing a bit more to get rid of that sketchy look and make the illustration feel more defined. If you're going to keep the linework, try to make sure it looks cleaner as well. Also, keep color vibrancy in mind when painting skin; use reddish tones in areas like the cheeks, nose, etc. Hope this helps!

"Hi there! I think if you are aiming for a semi-realistic style, the important thing is to focus on the lighting. Effective lighting will help bring out the silhouette of the face and give it a more three-dimensional feel. Currently, the colours seem a bit muddy, so I suggest making them a bit more vibrant. Additionally, you could add a rim light from the side. This will give the piece a dramatic, photographic quality (I hope that makes sense!)."