Nice one Joe!

To echo what Daniel said, there are at least two very well known proportion measurement systems.  One is Loomis another Reiter.  They only work effortlessly when the figure is standing and the view is from the front, but there are a few tips that you can use with certain body landmarks to check yourself.

There are a ton of great (free!) figure drawing/anatomy videos over at Proko.com.  They certainly helped me.  Here's a few:

A quick (30 minute) sketch of a composition that flashed into my mind's eye.  Call it "Little House Invasion on the Prairie".

I'm on the Flesk mailing list because I backed their Franklin Booth book Kickstarter.  Through the seductive magic on the internet, I wound up watching Terry Dodson (who's work I was/is unfamiliar with) quick-sketch this profile. 

I was captivated by how simple it was, and yet gets your brain to recognize it---so I tried a reproduction.  The process is always much easier when someone else leads the way (in permanent marker, no less!), and took just a handful of minutes.

Here's the original video link in case anyone is interested:

https://www.youtube.com/watch?v=k1hv4LvMNYU

I will say however that I feel that the ultra-simple character drawing style can, I think, be a slippery slope that might lead you to manga/anime-like cartoonish-ness.  In general, I prefer well rendered (but not excessive) detail.

Also, isolated character sketches of faces---either in profile and/or facing forward---are not particularly challenging perspectives.  The low-hanging fruit of the amateur sketcher, and probably child's play for a pro.