One of the most important rule while packing is be it for 1 week of 1 month of 6 months, pack just for 1 week. And you can wash and reuse the same for the other week or month. If you start packing 30 tops for 30 days you will never be able to carry your backpack. Make sure you have everything you need to survive for 1 week without much hassle and the rest will fall into place.
So things you need in a nut shell:
1. 5 pairs of clothes+ under garments+ scarf/ stole+ pyjamas
2. Jackets and umbrella+ sunscreen+ sun glasses + Mosquito Repellent
3. Unlimited Socks and shoes for wet cold weather
4. Toilet and medical kit+ towel
5. Dairy or a novel, wallet, pen, swiss-knife which can help you cut through anything.
6. Phone charger as without a phone nothing can happen these days. Earphones are also useful when you want some alone time.