Locate the g-spot which is around an inch inside. Just slowly massage in a back to front (and upwards motion).
You should feel the g-spot fill up with fluid.
As she relaxes you can speed up the moment and increase the upwards pressure. Just take notice of how she is reacting and feeling.
Now it’s up to her to let go and allow the fluid to come out. (You can also rub her clit at the same time at this point.)
You can make her squirt as much as she can take (or wants to).
Gently massage outside of her vagina after she has squirted as a way to finish off.
