While your hair mostly depends on your genetics;  stress, hormonal imbalance and poor diet have a great influence on your hair health and appearance. Start by following a good diet - Eat adequate amount of protein. Your hair is made up mainly of proteins. Include skimmed milk, cottage cheese, lentils in diet. Vitamin C, Zinc and Vitamin B are other important nutrients for great hair health. So include lot of fresh fruits, vegetables and whole grains in your daily diet. Next important step is to follow good hair care - Oiling your hair with a mixture of oils like olive, sesame, coconut and castor oil keeps provides moisture to your hair and prevent them from drying and breakage. Once in a week apply a good hair mask. You can mix and prepare different types of masks using green tea, olive oil, milk, gooseberry,  etc. Condition your hair using organic Apple Cider Vinegar, Rosemary tea once in a while. You can also start with zinc and biotin supplements. Consult on private chat for further help.

Following healthfeed should be helpful"Understanding Dandruff" by Dr. Jolly Shah Kapadia - https://www.practo.com/healthfeed/understanding-dandruff-8830/post