I've been to India. The last time I went was about 8 years ago so much has changed since then i'm sure.
Be careful when going into a shop because they can easily tell when you are from another country, even though you can speak their language. They are very good at ripping you off, especially taxi driviers...

Take someone who you know from India, they can't ripp you off infront of them.
You'll find cows, camels, pigs, bulls, running freely on the streets. When you go to sleep put over you one of those nets so you don't get bitten with flies.
Another than that I love the country and the culture. I think you should go now when you can though because the culture is fading and they are turning very modern.
Take toilet tissue with you

I'm sure most people have proper toilets rather than wholes on the floors these days... so you should be fine...