Cornflour is known as a dry shampoo
Take hand sanitizers and pour it on your palm. Then using you finger tips apply it on roots of your hair. This alcohol based products will works nicely for greasy hairs and will make them less greasy and another advantage of this product is, that it will evaporate quickly and you would not have to wash your hairs.
This is best and the yummiest smelling tip to get rid of your greasy hairs. Take a perfume spritz it on to your hair roots and keep a distance of at least 2-3 inches. Then using your fingers give your scalp a nice gentle massage. This will remove the greasiness of your hairs with a nice smell.