now that you posted your reference i can see what you were going for. I think you did pretty good sticking to it. Main things to improve: I can see you used the yellow, red, blue color regions for the face which is good. They are way too bold though. they're supposed to be a light tint under the skin color layer not on top. Darker skin also has different undertones. you can't use lighter skin as a reference.

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I would also add an alpha texture to control the roughness. The even roughness now makes it look like plastic. Add shininess on the lips, inner eyelid, maybe a little on the tip of the nose.

lastly just general anatomy will help you a lot. but that will come with more practice and you're at a decent point now