"Now palm your cock!" she orders.
You ask what she means.
"That means to rub the head of your cock in circular motions, using the lubricated palm of your hand. Start with slow circles, but then try faster ones, and vary between firm and light circles. Show me what feels good and gets you right on the brink!"
You do this and get very excited, but your hands slow down just enough to keep you from cumming when you feel yourself on the brink of orgasm.
"OK," she says, "Now make a snug ring with your other thumb and forefinger, just below your cock's head, right where the soft part ends and the hard-on begins, just tight enough that it's slightly difficult to pull it off and impossible push down onto the hard cock. This ring should touch the edge of your cock's head all the way around, and should be between the head and your sweet spot."
You follow her directions and find that you can now cup your polishing hand into a half-sphere shape, press it onto your other hand, and flatten your polishing hand just enough to make gentle but definite contact with the head.
She watches you and gets more and more turned on as she sees how horny and aching all this is making you.