|These were 1 minute drawings the top middle one was worked on after the pose.|
Ok so how do you learn to draw fast. Practice, practice, practice. As I wrote above I've done at least 20,000 one minute drawings, you have to practice, try to find a sketch class near you where they do a lot of one minute drawings. Unfortunately unless you live in a big city this can be hard to do; many people who go to sketch classes like longer poses, and think of short poses only as warm up. So you might have to talk them into doing short poses. At any rate always carry a sketch pad with you and sketch as many differant people as you can.
Next up I will tell you the one secret of learning to draw.