The first step in helping your partner achieve pleasure with a vibrator is to know how to actually use it on her. First, begin by lying side by side with her. Now, take the vibrator and place it between her labia and begin stimulating her clitoris. The trick is to begin slowly. If you move too fast, you will over-stimulate her and she will not achieve as much pleasure as when you allow for the sensations to slowly build. As she nears climax, gradually turn up the speed but watch for her body language. While some women enjoy more aggressive stimulation, many do not. At the same time, use your hand to manually stimulate her clitoris or labia. See what she enjoys and react accordingly. Again, watch her body movements. If she begins thrusting and moaning, chances are she is enjoying what you are doing. Watch for her feedback as she will most likely indicate (through her body language) what it is that pleasures her the most.
As she approaches orgasm, pay even more careful attention to her body language. Some women enjoy stimulation throughout their orgasm and cutting back too soon may impede their ability to fully achieve orgasm. Other women become over sensitive as they climax and may want you to dial back on the amount of stimulation. Again, watch her body language and watch for subtle clues that will tell you just what it is that she really enjoys.
If she is capable of multiple orgasms, figure out what you are going to do in between each orgasm and give her a chance to wind down in between without losing momentum. Many women actually learn how to achieve multiple orgasms by using a vibrator and so she may be pleasantly surprised how positively she responds to both your touch as well as the continued stimulation of the vibrator. While you are pleasuring her, lie between her legs. This will give you good positioning, better access, and a nicer view. While the vibrator alone can provide substantial pleasure, many women will also enjoy your touch in addition. Use lubricant as you gently stroke her clitoris and labia and remember that these areas are very sensitive and will most likely become even more sensitive as you apply the vibrator. Try moving your fingers in gentle circles around her labia and then gradually move to stimulate her clitoris. Watch out she responds and if her body language tells you to stop, make sure you stop. And if she tells you to go, then go go go!
And, most of all, when she does climax be supportive and watch her rhythms. Work with her body language and be mindful of what she enjoys. When she is finally done, be prepared to either lay beside her quietly or make love to her if she wants to continue. Used properly, a vibrator can greatly enhance your ability to give her pleasure and can ultimately help you identify what it is that she really enjoys.
