Need some advice on character modeling

I want to begin learning again on how to model heads, I never was very good to begin with, however I did find that I could easily box model the basic head shape, but filling in the details was a bit beyond my understanding. My problems generally seem to revolve around the fact that I can make the eyes look great, or I can make the lips and noes look great, but combining the two together in the same mesh always seems to be a problem. I’ve tried the loop method, but that doesn’t really work for me, can people who box model heads give me some advice on how to make my facial details look better even in a low poly mesh which is what I have been attempting