I am taking a class on animal drawing at the LA Zoo (through the animation guild) and I had a pretty successful first week. The teacher wanted us to loosen up our work and try drawing without looking at the paper, use continuous linework, or draw with our off hand.
My most successful drawings of the day were partially blind...i'd occasionally look down to see if I was more-or-less on track. what I liked about them was the fact that I got in so much more detail then when I tried to use the construction approach to building the animals (think boxes and spheres to create the volume).
I also used my brush-pen a bit and enjoyed working with that too.