I don’t think I’ve a particular technique in doing sketchy heads… but sure it’s not magic ahaha X°D
Since I’m not good in words, you can see it with crappy gifs:
(why it’s pink oh well)
in the rough version I work with a soft and fat tool, not caring about details, but only on general appearance and mood. the crow is basical in this, because it gives me the idea of head direction and eyes line.
then new level and ink/clean version! There I choose better the expression, and all the tiny details like hair. A lot of people will yell at me because I don’t do a middle level between the rough sketch and the clean up, that “you can’t draw a good thing without a good sketch base etc etc”. I say: it’s true, I’m not a good example to follow, but I like more this way. More sketch levels you do, more precise and correct will be the ink, but you’ll lose a lot in acting and natural drawing. That’s just my opinion.
Also don’t be afraid to redo/clean/erase stuff. We improve from our mistakes, don’t let them beat you!