Surto: I'd say start by practicing to boost your stamina - longer and more extended stimulation should build up to a larger orgasm. If you already have good stamina, you can always increase the intensity of the feeling (not necessarily harder, but focused on where and how touch is most sensative to your dick). Two, if you recognize that your dick is very sensative after you cum, try to suck that feeling into your body rather than outward. Once you can feel it inside before it projects out, you should start to have some control over it. This "shaking" doesn't always exactly mesh with your cumming but it often does. Keep practicing. This should give a very long and explosive orgasm, with preliminary tremors and after-shocks. Some of it can also be mental concentration. Try getting rolling a little slower and really try to focus your mind on the sex (whether you're actually going to fuck or just beating off) - so that its not just your physical senses turning you on but your mind too.
Mademoiselle: I agree that one person is never going to completely feel or understand what another feels, and definitely that each person is best off to be responsible for his/her own orgasm. But I don't see why one cannot enjoy his/her partner's orgasm physcially as well as psycologically - the warmth, the tightening grip (hands and vagina), the pulsating - those are all outstanding physical sensations. It definitely adds something to the sex for me, even though I am not in direct control of it. Actually, I think that the more responsible for your own orgasm you are and the better you know your body and its responses, the better chance you have of doing things in a mutual way (or recognizing if you can achieve it with a particular partner).