-Don't use any harsh hair products because they can strip your hair of natural oils, which causes your hair to produce even more oil
-Try to wash every other day OR wash everyday except on the weekends to let your hair get back its natural oils
-Try using a powdered shampoo, these are really good for oily hair
-Use a bit of baby powder at the roots to absorb excess oil. You don't see it and it smells good.
-Don't use a lot of extra hair products and try not to touch your hair with your hands because this can make your hair get oily faster.
-If your hair gets oily around your face, use blotting sheets on your face or powder to keep your hair from getting oily.
Good luck :)