hmm. well, as a girl, I can tell you it is very important for the guy to ENJOY what he's doing. for example, if he looks up from giving the girl oral and has this "god, are you done yet?" look on his face, it totally ruins the moment.
also, a lot of guys underestimate the power of compliments. most girls will be at least a little embarrassed about being seen without their clothes, so a few reassuring comments of "wow, you look hot," or "you have great legs" or something goes a long way.