1 Ejaculation and orgasm are not the same thing
2 Unlike women, men do not plateau. The best experience derives from a monotonic - and fairly short - climb. Either let him cum quickly first and then again - more slowly - later or concentrate on yourself first. Do not bring him almost there and then decide it's your turn - he'll never fully recover and the phrase damp squib might come into play (see 1). It follows that there is more chance of finding an honest second-hand car dealer than of obtaining the Mills and Boon fantasy of climaxing together.
3 During ejaculation his cock may become extremely sensitive. If you offer to let him cum in your mouth (as opposed to into your mouth) and he politely declines do not go off in a huff. It may be that he knows this will simply be painful and prevent a proper orgasm (see 1)
4 Orgasm will have been achieved if the body shakes violently at the hips and this transfers up the torso in a kind of solo mexican-wave, culminating in whiplash. If, on the other hand, he simply shakes his head and asks you if you "fancy a cuppa" it was just ejaculation.
5 During the first few minutes following an orgasmic ejaculation a man is in a state of total and divine relaxation. This period should really be regarded as part of the orgasm; in fact it is the only part that we actually experience. During an orgasmic ejaculation all body function is directed to involuntary movement and nothing reaches the brain till afterwards. Please let us enjoy this. We do not ask questions or hug you tightly or start stroking random bits of your body as you build up to an orgasm. The entire body can be sensitive during this period and engaging the brain to say anything at all destroys the magic of this blissful period.