Cool goblin work! I am guessing it is for the goblin assassin CHOW I see . Try to draw from life as much as you can e.g Mirror self-portraits, attending a life drawing class, drawing your own hand, pretty much anything and everything. That way you exercise your brain at a higher level by trying to put down three dimensional form into two dimensional paper rather than two dimensional form(photo) to another two dimensional medium. I see you already got a head(pun unintended) start on it which is working on your head construction their are plenty of books on it(Andrew Loomis - Drawing Heads and Hands, Bridgman and plenty of other good ones) if you want to for example try and match a face up with a certain personality try to study facial proportions of actors or models who you think portrays these characteristics and do studies of them.