If you shampoo your hair too often, that could strip off the natural oils. The scalp then compensates for the lost oils by overproducing sebum, leaving your scalp greasy. Use dry shampoo and conditioner and wash your hair about twice a week. If it is too oily, you can wash it every other day to avoid build-up. Follow up the shampoo and conditioner with a light leave-in conditioner and apply moisturizing and nourishing hair cream or oil for the dry ends.