This is a great game to play, and tells you an awful lot about what he would enjoy. With the caveat that all men really are different in their tastes, I can make a few generalizations and give you a few tips about what most men like. Although a little light breathing on a wet penis can be quite enjoyable, I have yet to meet a man who actually enjoys a woman blowing his penis. Next, many women underestimate how much pressure they can exert on an erect penis when a man is aroused. Remember, your clitoris has far more nerve endings per square inch, so using how much clitoral pressure you like as a guide doesn't work.
Many men complain that far too many sex partners simply bob their heads up and down.
Lick, nibble, go up and down the entire shaft, flick your tongue across the head. If you do the same motion repeatedly, your partner becomes temporarily insensitive to it, so be sure to vary your motions. Most men enjoy their partner adding to the stimulation from her mouth with her hands. You can lightly rub his testicles, let them roam elsewhere on his body, or whatever. One particularly good technique is to use one hand to make a tunnel around the shaft of his penis.