The Start Stop Technique: The basic technique is stimulation of the penis until just before the point of orgasm, and then stopping stimulation until arousal is lower. Start stimulating again and the process is repeated until desired length of time until orgasm is reached, You may lose your erection when you stop the stimulation, but just start again. The most Important part of this exercise is to try everyday if possible. This exercise may take 3-5 months for improvement.

Pelvic floor muscles: Stop the flow of urine while you are peeing. As you are peeing, intentionally stop the flow of urine. Do this several times until you can clearly feel the muscle you are using to stop the flow.

http://www.sexualweakness.com/premature.html

In my experience with this issue, the best way to deal with it is to figure out the source. In most cases I’ve seen where it’s happening regularly, it’s gone away with a reduction in stress. There are also numbing creams, and Trojan sells a condom called "extended pleasure" I believe which contains a numbing agent to help reduce sensation and thus delay orgasm.

Also, you can control the problem by taking a break from intercourse if you feel you’re going to climax too quickly. More foreplay at the beginning, and taking breaks during intercourse to pleasure your partner while you let your body calm down a little can be helpful to make sure that both you and your partner come away from the experience sexually satisfied.