Press your thumb against her clitoral head and gently flick it from side to side as you penetrate her with short shallow thrusts. Or press the shaft of your penis against her clitoris and then gently thrust between the folds of her labia without ever entering her. Or she can perform Kegels (the squeezing of her pelvic muscles) while you, ever so slowly, penetrate her. Really take the time to feel her pelvic muscles contract against your penis as you slowly withdraw.