Hi Andy, 
Good to see your studies! One thing I might recommend with respect to charcoal media is getting a sandpad such as they sell at art supply stores, and sanding down your charcoal to a point. That will give you the ability to draw with a variety of thick / thin lines, whereas with blunt charcoal, you can only get a thick line.
Not that you have to use charcoal pencils, but I recommend them (6B, soft) because they are not nearly as messy as sticks and they are easier to sharpen with an exacto and sand to a point - this post shows what media I use:
http://www.foundationalarts.com/cgi-bin/forums/ikonboard.cgi?act=ST;f=12;t=12
Try seeing what you can get with line only - no tone. Experiment with thick and thin lines - a thin line will make the form recede in space, a thicker one denotes what is nearer. I also highly recommend trying several master copies in charcoal - for example, by Rubens and Michelangelo. It will really teach you a lot. 
Cheers,
-Rebeccak