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.
Breath. It is equally important, maybe more so, that the cock doesn't stink. I am not kissing. I am getting my cock sucked. It has spent most of the day in a poorly ventilated sweaty area, and upon being pulled out for some nice sucking, it may be a bit stinky. Please just suck it.
Deep throating. Disclaimer. No one has ever been able to deep throat my cock. The first time a person is sucking my cock is no time to attempt deep throating it. My cock is very sensitive and I really enjoy having the head sucked. Shaft licked. Balls sucked. I don't enjoy gagging or being wretched on. Just suck it please.
I really don't want to talk about it. You want to suck cock. I want my cock sucked. Just do what you want and do well. Afterwards, We can talk about how you did if you want. But I don't want to give instructions, move your head, or anthing. Just suck my cock please.
I do enjoy have hands on my cock shaft, jacking it, while being sucked. I have enough cock for that to easily happen. If you like to do that, go for it. Keep the head in your mouth.
And finally, you have to take the cum in your mouth. Where it goes from there, I don't care, but just suck it out.
I know teeth can hurt a lot, and a few scrapes of the teeth can wipe out the past five minutes of incredible cock sucking. Too much teeth literally makes me go limp.
Most guys want to go real fast, and expect a big, quick load. That doesn't work for me at all. I have to keep reminding them to slow it down. I feel it better, I get harder, and then I start twitching and cum much more quickly.
I get harder when I'm stimulated, and I'm more stimulated when I get harder. A little pressure on the top of the base can keep me a bit harder, or an angle that pulls my cock down from it's more normal high angle can get me harder and can make it easier for me to cum.
As for cum volume, for me a longer, slower sucking that borders on edging can help me pump out more semen than usual, and can often lead to a higher pressure cum fountain.
When I suck I like to get him nice and wet. More lube feels good. I like to keep more pressure around the crown of the head, and use my tongue to add some tickling to the frenulum area. Every so often I'll swallow deeper to stimulate the shaft. And I try to keep some stimulation of the man's balls going on too. Sometimes I'll use my hands to rub around his thighs and belly area, or reach around to his ass. These things might help, I know that they work on me.
Some moaning doesn't hurt either. I know it feels better when the sucker seems to really enjoy themselves. And when I am enjoying myself with a cock in my mouth, I like to let them know that I really, really like it.
Also don't forget tip #6.a.: When the guy is about to cum, place a finger or thumb gently against the spongy urethral portion of the cock near the base, so that you can feel the contractions while he squirts his load out. or make sure your lips are positioned well against that part of the cock if it's in your throat, which I can't do unfortunately but I'm sure it would be totally amazing