Make it really wet, suck and lick the clit (tongue flicking a clit is not as effective as it looks).
A couple of can't miss gimmicks is to run a finger or two up and down the length of her slit (primarily the spot just below her clit, just inside her lips but not quite inside of her twat) while you suck or lick her clit.
Suck or lick her clit while you use your thumb to rub the bottom of the outside of her puss...(opposite end of the clit) in a circular motion.
When you get her worked up and she's nearing lift off and she starts to moving her hips....slowly put your wet middle finger on her asshole. Apply a little pressure but keep it in one place and allow her motion to cause her asshole to move over your finger. Don't try and poke it in....when her engine is humming full bore...she will likely position her asshole to take your finger in on her own..
When she's orgasming, slowly but firmly massage her inner thighs at the same time with your hands.
Last but not least, just before she cums and you're sure she's ready to cum tell her to relax her whole body.:2 cents: