It doesn't take a chick to help you with this. Try sucking on her clit and reach inside and rub the G-spot. When you are sucking the clit, rub it with your tongue. Press on her asshole, too, that adds stimulation. I try to stimulate three things at once with my wife to produce a badass orgasm. Pinch a nip with wet fingertips and twist or pull while you are working the clit and pressing the asshole. If she screams my name, let me know.