Are you experiencing premature ejaculation or just want to delay orgasm?
If it's premature ejaculation, you might want to see a doctor, or seek medical advice.
I'm not sure that I have any advice to help, as I don't have this problem, if anything, it's the opposite for me, it takes me a bit longer than most guys to reach orgasm.
I don't like quick sex for that reason, I like to have time to let the orgasm build.
I have heard of creams that you apply to numb the cock - it decreases the sensation and should dely orgasm. Not sure how well these work.
You can also try squeezing your cock when you feel the urge to cum. Grasp your cock head with thumb and finger (base of cockhead, on the shaft) and squeeze hard when you start to feel like you're going to cum. I've tried this, and it does hold off cumming, if you're not past the point of no return. You might want to try this when jerking off to see how you respond.
You can also try varing your activities when you're having sex, so you don't get "in the zone" so quickly. Keep your hands off your dick when you're pleasuring someone else. You could also try jerking off prior to having sex with another guy. Not right before, but a couple hours - that might help to delay orgasm when you're having sex with someone else.
Maybe some of the other guys here will have some suggestions.
I remember hooking up with this one guy when I was in college. We'd get naked and get started and he'd cum in about 5 minutes. I was just getting warmed up. After he shot he was done. I just left blue balled. After about the third time he said "I want you to cum next time" - and I said, fine, but you've got to slow down and at least give me a chance. I don't think we did anything after that.
Some guys just shoot quickly, but that doesn't make for the best sex. Be attentive to the other guy so you're not so focused on yourself. Reaching orgasm is great, but getting there is the best part.