Quick little oral sex technique:
Before going into the awesome and powerful oral sex techniques I have shown in my blog, try warming her vulva up by writing her name on her labia and clitoral hood–very lightly–with your tongue. The center of each letter should be the clitoris, so that the tip or glans of the clitoris is only lightly brushed every once and a while.
You can even write a nice love note or poem down there.
Usually the orgasm comes from repetitive, light stimulation that becomes increasingly vigorous. But this kind of unpredictable pattern should get her started right.