Just a few things that come to mind for India and Nepal:
You WILL get scammed and cheated. Don't worry about it, accept that it will happen, and just hope you didn't lose too much. We were almost constantly hustled and cheated while in India, It's really easy to get cynical with scamming locals, dishonest drivers, relentless lying touts, and fake "friends", but try to stay fresh and open, and don't withdraw into negativity.
Take lots and lots of passport photos. Like, at least 20. You'll need them for lots of strange government things.
In Nepal you can get sim cards anywhere, it's easy, you just go in with money and buy one. In India, the best place for getting sim cards for your phone is at the airport. It's difficult elsewhere due to the maze of paperwork and ID required. Google it, and make a list of all the ID stuff you need to give them to get a sim card. And tell them you need it to work in all of India, or the specific states you are going to. Otherwise it won't work when you cross into another state.
My iphone was SOooo useful there, looking up stuff and good hotels and what the taxi price should actually be, and booking trains, etc.
Travel as light as possible. Take almost nothing. Try to get your luggage below 10kg. (apart from what you are wearing.). Do not take a laptop. You can buy everything there. Everything! It will all be fake, but it will be almost as good as the real thing.
The latest edition Lonely Planet guidebooks are really good, both the Nepal one and the India one. That'll be a big chunk of your 10kg weight though! I had both the e-version and my brother had the real paper copy, and we used the real book much more. It's worth going into a bookstore and getting before you leave. Might be a bit late for Amazon unless they do fast shipping.
Have a cool time.
saturated with joy,
you will put an end to suffering and stress.