stress is said to b one of the causes but ther r plenty of other factors.
i had lots of dandruf but now its in control. i oil my hair weekly at night and wash it in the morning - oil softens ur hair and also makes ur scalp less dry.
u can try - Dancel Shampoo everyday.
If u r talking about hearbal treatment, u can try to get Neem leaves. Paste it and use it in ur scalp for half n hour.
Dont throw banana peel - blend it with sour yougart and use 2 table spoon of lemon juice and apply it all over the hair along wth the scalps.
keep it for 15 to 30 mins at best and wash it wth shampoo.
Never pour warm water on ur head. Always use cold water.
keep ur hair clean and avoid going under scorching heated sun.
lemme knw if my suggestion was of any use :-)