What can I do to prevent vaginal dryness due to menopause?

A few ideas. Topical estrogen, in the form of cream, pill or ring, is best. Estrogen is what gets depleted in menopause, so replacing estrogen with estrogen will give you best results. Otherwise, use water based lubricants during sex. Can try OTC product such as Luvena or other probiotic based products to help encourage lactobaccilli growth. But basically, estrogen is what keeps vagina moist.
Creams. Having intercourse leads to natural lubrication that will help the dryness. Over the counter you can find products such as Replens that used vaginally can restore the mositure to vaginal tissues. There are also prescription vaginal creams, patches and pills that can help. You are still young, but if are experiencing signs of menopause, see your doctor.