I continue to sketch every evening on a daily basis. I like to use a variety of reference books to make the process both interesting and challenging.
I recently purchased the book, Character Mentor: Learn by Example to Use Expressions, Poses, and Staging to Bring Your Characters to Life written and illustrated by Tom Bancroft. Here's a partial description of the book from Amazon:
"Character Mentor shows you how to pose your character, create emotion through facial expressions, and stage your character to create drama."
There's a lot of good solid information in the book. (Full Disclosure: I have no association with Tom Bancroft). Check the book out online or in a book store.