Practice is everything to us self taught ones eh? Thank you, @anouk.nox! And allow me to add, I have practiced Bargue Drawing, and it helped me tremendously with my values and proportion in portraiture and figure drawing. You can check out THE DA VINCI INITIATIVE in YouTube. They have a free tutorial that's basically everything you need to know to start Bargue Drawing. :) I hope it'll help you as much as what it did to me. Cheers!