Yousa, have u ever read a bit of Loomis book about drawing the head and hands?
I know the whole selfportrait thing seems like a lota fun but if u havent yet, study loomis book on the human head construction, at least in parallel to this.
I hope ull trust me and do it.
Im currently studying this book and im in total love with it, Andrew Loomis was, i believe, a great man.
Good luck to u!