This one is tricky. I used to think my previous girlfriends had multiple orgasms before I would announce my intention to cum in earnest. But I found out later through various levels of arguments that a lot of those reactions during sex were for show, to turn me on, and to build up my confidence to convince me to cum. One woman confessed she really only has orgasms with a combination of rubbing her clit herself while pressing that industrial strength Hitachi vibrator wand right in the middle of all the action.
Anyway, usually I would have a goal to help her reach an orgasm first, at least once, before I would no longer hold off myself from cumming. The tried and true method was her on top, me on my back, her riding my cock cowgirl style, with her in full control of not only how deep, but also how much pressure she wanted to use, to grind my stiff shaft right across her favorite spot. It felt like her pelvis bone was going to break me in half, causing her to have an intense orgasm.