A pretty awesome guy named Stan Prokopenko started a video series on Youtube where he covers the basics of Andrew Loomis' art, with an absorbing teaching style that makes them fun to watch as well as being very informative. There are a lot of aspects of the construction of the face I didn't "get" until I started watching (especially with the placement of the jawline and relation to the neck when the head's tilted upwards) and I definitely feel like I've improved by working through them. If interested, you can find them here
I also started playing around with Sai's brush settings and was able to replicate the look and feel of drawing with a pencil (which you can see on the eye and nose), and am now totally comfortable drawing in the application. This was a great warm-up for the 5 Hands assignment in the Sketch-Books
group which I'll start working on right now.
C&C is always appreciated! I'll move this image to scraps in around a week and upload a revised version with facial features added to the head templates.