If it's hormonal, there might not be much you can do about it except wait for puberty to pass, but my doctor recommended a gentle face wash like Cetaphil, and the lowest dose benzoyl perozide cream - I think Neutrogena has a 2.5% cream for everyday use (On the Spot?). The normal 10% that most benzoyl peroxide creams come in can be just too harsh for everyday preventing breakout use. Also making sure to change the pillow case often can help.
If it's really bad, you can also try cutting back on dairy. I've read some
studies about how the hormones in milk can contribute to acne, and at least anecdotally for me, I find the less dairy I consume, the better my skin is (which is hard, because I love cheese and ice cream).