Drink more water and use Cetaphil cleanser and moisturizer. It's gentle and moisturizing, and you can get a lot of it for a decent price (it's pricey for drugstore stuff). My friend is undergoing Accutane treatments right now, and that was the dermatologist's recommendation.
Also, get a washcloth wet, squirt a bit of Cetaphil cleanser on to it, and use the washcloth to wash your face GENTLY, moving the cloth in small circles. Only do this once a day. This will help exfoliate your skin and get rid of any dry flakes, allowing the moisture cream to get into your skin more easily. Also put the cream on within THREE minutes of washing your face--onto a still-wet face. This will help seal in the moisture. At night, put on an extra layer of cream and let it soak into your face. That should help as well.
ALSO: Don't use super-hot water to wash your face. Use lukewarm water.
Hope that helps.