If feel like I'm butting in here but I have to agree that learning anatomy is incredibly important. Personally I'd reccommend going to life drawing classes as you learn so much (especially if you are asked to draw from 30 second poses) plus it's a complete buzz to draw from someone whose directly in front of you.
Look around you as well, watch how people move. Another useful tip if you need to come up with a pose snip the pictures out of newspapers and you can study the pictures and how people stand, hold themselves.
A bus station is where a bus stops. A train station is where a train stops, I have a work station.