There's a book by the venerable Preston Blair called "Animation 1." It's incredibly cheap and regarded by my animation professors (themselves from Disney) to be the best resource for character construction on the planet.
Check out the Amazon link here: [link]
The best part is you don't even have to buy it. The first and most important pages are free to preview. They cover full body construction, expression, line of action, and skeletons.
And of course, send sketches my way at any time or mark them for critique. I like the stuff you do. If there is any way I can help out, I will do so.