Refer to the few checkpoints before you start packing your bags:
First, check the season. Is it summer or winter when you are travelling!
As both the weather conditions can reach extremes so it is better that you pack according to the season.
If you are traveling in summers, pack light cotton clothes. Do not wear synthetic as you may develop some skin allergy or heat burns. Sun-hats or caps, and sunglasses are highly recommended. If you are travelling to the hills or mountains then you will need light woolens during the nights.
During winters, pack some warm clothes, as it can get mercilessly chilly in some parts of India. In the south and in the hills, you will require woolen jacket during the evenings and early morning. In the north, you may need to dress warmer in woolens even during the day as it gets really cold. Its best to carry a small day-pack to keep some clothes in as the day gets hotter.
During monsoons, quick-drying clothing, and either a raincoat or an umbrella is advisable.
You must carry good sturdy sport shoes with you while travelling.
It will also be a good idea to carry a light stole or scarf with you with which you can cover your head in case it gets too hot. Also, in some religious places one is required to cover one’s head, so it may come in handy.