For face studies, you should focus on drawing from life. Gather some photos of people (friends are fun to do) and do portraits. You'll expand your visual library this way. If you wanna get more in-depth of structure drawing some skulls is a good idea.
the colab is fun. But I can't read what's written in grey :( secret stuff Your latest piece is also looking good. Only the clouds are somewhat to abstract and flat in comparison with the rest of the painting. But maybe that is what you were going for? Btw I like your logo!