its all about hitting her gspot and rubbing her clit at the same time, when she starts to cum slide your finger in her ass. hottest thing ever is when a girl instantly grabs u by the wrist with like super human strength and pulls your hand in just a bit deeper cuz shes that hot for it. and remember your cock is in her mouth and in my experiences while this is going on your getting amazing head because your getting her off so well.. plus the feeling of being deep throated, her cumming intensly, she will start to whimper while your cock is in her throat... im telling u its a great sensation. ive started many a session with high $$$$$$ escorts that id wind up staying long past my time just cuz i can get them off like this. what can i say i enjoy getting girls off and when u really do, they can tell, and appreciate it and its VERY rewarding.