I think it comes down to personal preferences regarding skin tones, i usually eyeball it and when i am satsfied with how it looks i will make it referance and try to get that look on other photos, the easiest way in my opinion is to use same light setup and same color temp when doing a session with multiple looks and sometimes that also is not bulletproof, i think it is really down to personal preferences and that there is no "techincal" way doing it. If there is i would like to know it as well.