Hello, Fai, and welcome aboard, how are you? Greatest job on how solidest but most organic you drew the forces, shapes, and forms of the human heads, but the tilt could be the most clearest yet, so how would you like to try out 5 minutes of 30 second faces, heads, and expressions here on this website, along with the livestream of Mike Mattessi on Drawing Forces on heads here?:
The real reason is because, you can and will make lines of action more softest but lightest in terms of your character design's internal thoughts and feeling. For most details, see more of the Mattessti Livestreams please.
Let's hope this here livestream helped and supported you the most!