
To figure this out, think about the kind of stimulation that really gets you off. Is it light and fluttering, or deep and penetrating? Localized on a small area of the clit, or do you prefer stimulation over a larger area? Women who enjoy light, localized stimulation might enjoy a pocket rocket vibrator with an attachment, bullet vibrator, or a strap-on clitoral stimulator, while those who like stimulation over a broader area might prefer a Hitachi Magic Wand.
And speaking of penetration, vaginal penetration isn't necessary for a woman to get off. Penetration can make orgasms more pleasurable for many women, but most women respond more quickly to simple direct clitoral stimulation. Likewise, massaging the G-spot inside the vagina manually or with toys may increase the intensity of a woman's orgasm, but usually doesn't bring it about directly. However, if a woman enjoys simultaneous clitoral and vaginal penetration, she would probably enjoy a rabbit-style vibrator, or a G-spot stimulator with external nubs for the clit.
Once you find the right vibe, you need to find the right spot to get you off. This may be directly on top of the clit, or off to one side. Move the vibrator around until you get in "the zone" and then stay on top of the sweet spot. This should have you over the top in no time.
Can a vibrator give me my first orgasm?

Sexuality—Learning About Orgasms
Can I use a vibrator help me orgasm during intercourse?
I'm still a virgin. Will a vibrator help me get ready for my first time?
If I use a vibrator, will I still be a virgin?
What is the fastest way to reach orgasm?
I still can't come. What am I doing wrong?
My vibrator isn't getting me off anymore. What's wrong?