It's one of those skills that would be hard to teach, as it's not just about technique, it's about the individual you are doing it to. For instance one man may enjoy it quite firm and fast. They might even like to feel the teeth a little, while another would hate that and much prefers to feel the tongue gently rubbing up and down the shaft and maybe the mouth plunging over and off in rapid motions.
Basically you could teach various techniques, but unless they are applied to the right person they could be the best or the worst experience ever.