Start out with lots of kissing and rubbing of all her erogenous zones; make sure she is wet and excited before you go any further.
Kiss your way down to your clitoris and circle it with your tongue, then as she gets more flushed and excited, flick your tongue back and forth across it while sliding a finger in and out of her.
Do this until she reaches full orgasm.
Once she has recovered from her orgasm, slide inside her with your penis.
Stroke deeper and deeper until you reach full insertion.
If you're well-endowed, the tip of your penis should reach her cervix.
At this point, raise her legs to your shoulders.
Thrust in and out of her with your penis angling downward; this will allow your shaft to create friction on her G-spot while your penis base stimulates her clitoris and your tip tickles her cervix.
If you can create enough friction this way and last long enough, she should reach full orgasm quickly.
Stroke shallowly while she recovers again.
Then keep her legs in the air but spread them apart more.
She should be very wet and loose by now, so this is where the fun begins.
Pound in and out of her as hard and deep as you can.
You should be able to get her screaming and talking very dirty and nasty by this point.
The more intense you can be, the better.
She should easily have 3-4 more climaxes this way if you do it right.