For oily hair use plain amla powder as a hair wash or Triphala powder (plain), a classical Ayurvedic preparation can also be used.Make a paste of either of these powders, apply it on the scalp, retain it for 20-30 minutes and wash with cold water as and when your hair gets oily. There is no harm if you wash your hair regularly because of its natural trait. For the dandruff, especially during winters, soak scalp in lukewarm sesame oil for an hour and wash hair with luke warm water. Use shikakai to wash hair.