Take his cock as deep into your mouth as you can. Start to move up and down the shaft very slowly. As you move up and down, with your lips firm on his shaft, draw little figures of eight with your nose. Make them about three or four inches across. After a few strokes reverse the direction of the figure eights. Swirl the tip with your tongue whenever you can reach it.
This drives my master wild!

He also like me to open my mouth slightly and breath in on the upstroke, this cools his cock. Then I breath out on the downstroke, and warm it back up again!