It is highly recommended to stimulate her clitoris with your tongue while performing this procedure. It should also be noted that stimulation of the g-spot through multiple orgasms will often have a cumulative effect. Even if she is the quiet sort, you can tell if it is having this sort of effect, because her vagina will flutter and convulse with increasing strength as her orgasms progress. Also, the length of the orgasms will tend to increase each time. This can be very tiring for the woman, however, so she probably won't be able to take very many.
Afterwards you must feed her chocolate and stroke her hair... don't stuff your dick in her mouth, or make her tell you over and over how great it was.