Holo has got it good. Just what I was going to say..
For my wife, giving me a blowjob turns HER on too, and the only way to get really good at it, is to be into it in the first place.
She'll deepthroat me and tell me before she does, getting me anticipating and very hard, then when she does it it is just SOO sexy for me, and she enjoys. Only deepthroat in moderation though, the whole time gets boring. Remember to be random, and don't do the same thing too much..
And best of all, DON'T STOP until he says so or you have to
Good luck.