Just a quick note I gave one of my students recently regarding drawing story boards for their short film.
The early story board pass just try to keep things simple.
I drew them these quick examples on the cintiq where by just having very simple lines for the characters eyebrows you can very clearly show what the expression and attitude is.
Keeping it simple so you can experiment with your ideas and not having to worry if you need to change the ideas or throw them out and start again, only to make it stronger.
The idea is to really try hard to make it work but keep the drawings as simple and as clear as possible to tell the story. Oh yes, they also wanted a few 'simple' hands as well ...