HI Neysa. I Really like what I'm seeing here for a foundation, evrything is right where it needs to be, the rest is a decision on how far and to what level you wish to take it. Right now the drawing is very monotone, there's not a lot of contrast and contrast is everything to a drawing. The one comment I see most in this forum is artist afraid to go "to dark". Afraid to add Deep shadow for fear they will go to far. This exactly what this piece needs, a shadow push! And that's pretty much it!
I Usually use Charcoal for my shadows, a lot of people use 6-b Graphite. It's your call. This is your masterpiece!
Just build your shadows slowly and blend them out with cotton or chamious. Do this and you won't push it to far. I've attached your drawing after some photoshop work to show my point.
I really think you will see Tyler leap off the page!
Have Fun!
Marc Forest.
http://www.marcforest.com