First of all we will consider some common reasons for early greying...
If early greying running in your family
You are having a pitta predominant nature
Using spicy food predominantly
Experiencing increased mental stress
Due to some environmental factors...etc
So avoiding usage of spicy food, beverages, taking a well balanced diet, include gooseberry, sesame, greengram etc in your food, regular exercise,try to get a good sleep atleast 7 hrs, drink sufficient amount of water..
Take one teaspoon chyavanaprasa before bedtime along with milk (if you don't like milk lahya alone is enough)
Neelibringyadi kertaila can be applied on hair
Next Steps
consult an ayurvedic physician for detailed investigation
Health Tips
pranayama and meditation can be done