I swear by kegels (i'm a man). The way to do them if you're a guy is to just act like you're trying to get that last drop of pee out while urinating. The muscle you are flexing is your PC muscle. Start out with doing 100 or so a day, and work your way up to 200 or so. As long as no one is staring at your crotch, you can do them anywhere.
And yes, kegels helped me a LOT with how long I can hold off an orgasm. I don't do anything special to acheive that, I just have sex normally and the magic happens.