Greasy and oily hair is normally a result of an overproduction of sebum in your sebaceous glands. It can also be caused by your choice of food, your hair-care routine, stress or health reasons, or by your genes.
A good idea would be to make some changes in your diet. Try to cut out greasy food and eat more fruits and vegetables.
The first impulse would be to wash your hair more frequently with a strong shampoo. This would, however stimulate your glands to produce even more sebum. Use a shampoo which should be rather mild but absorbs fat and dirt on the scalp and hair.
As a conditioner look for products containing mineral earth, which not only helps to absorb the excessive oil but also helps to clean up scalp irritations. A herbal rinse based on apple cider – applied once a week – will help to break down the oil. You can also look for a hair-tonic based on medicinal herbs to normalize the production of sebum and help the circulation of the scalp.