Looks good! I’d add more volume to nasolabial fold, as it looks a bit flat there. Also you could make the nose bones a bit more defined, where it meets the skull.
About poses, I myself want to study it, I’d check materials from animation, like these https://www.youtube.com/watch?v=KsW3jGtmNtA&list=FLLHK1Nw-XmRWrPx0J77FjAg&index=4
Also there’s posing for photos, I think it’s an interesting subject as well
https://www.google.com.ua/search?q=posing+in+photo&num=100&source=lnms&tbm=isch&sa=X&ei=yOwaVbLHNIWcsgHa54KIAQ&ved=0CAcQ_AUoAQ&biw=1536&bih=777#imgdii=_
And yeah, perhaps this book also has interesting points!





























