Some things I can't over-emphasize the importance of when it comes to giving an amazing blowjob (i.e., amazing for both you and the recipient).

1. Have nice breath. It's your mouth that the cock is going into, how much of a turn-off is it when the suckee has to smell nasty breath?

2. You might like sucking cock a certain way, but the suckee might also like getting sucked a certain way. It's only common courtesy for the sucker to say something like, "If there's a way you like it sucked, I take direction well." Some guys like the hand stroking the shaft along with the sucking motions, other's don't. Don't you want to know if your recipient likes it one way or the other? You're more likely to get a hotter and bigger load that way, your reward for extra pleasing attention. I know I like use of hand stroking, it'll almost surely get me off before long, but I'll usually let the sucker suck it how he wants and that gets me off too, just imagining what my hard cock and shapely spongy head feels like for the sucker.

3. Make sure you know how to deepthroat properly if you're going to try or do it. Same suckers can't seem to work it past the rear of the roof mouth properly, putting a lot of uncomfortable/unpleasant pressure against the head and shaft. If you want to use your throat, make sure ahead of time that you know how to do it without resistance using a dildo or something, or start with mild throat action to make sure you're getting it right.

4. If a guy shaved his balls really short or smooth it's probably for a reason: he would enjoy some attention on his balls! It's also a sign that he "takes good care" down there enough to thoroughly wash and smell nice/neutral if you went down there to put those smooth balls in your mouth. You especially wouldn't want to miss out on the low-hangers as they give you more silky smooth flesh to play with. At the very least fondle them gently and lustily if they're hanging right out there for you to play with.

That should be enough for now. I swear if you're attentive enough to follow just these rather simple rules, the sucker and recipient will probably both have an amazing time.