One of the most important things you can do to keep from getting sick in India—or anywhere else, for that matter—is to wash your hands before you eat. If there’s no water, use some of that waterless hand cleaner, which is pretty easy to find in India. Personally, I like the one that Himalaya makes.
The thing is that India is overwhelmingly a cash economy and it is nearly impossible to avoid handling a lot of currency unless you are so wealthy that you can have someone else do it for you. But did you know that nearly all Indian coins and banknotes are contaminated with at least one pathogen that could cause a severe bout of Delhi Belly, bronchitis, or even worse miseries? Yuck! The Indian government is planning to introduce plastic banknotes in the hopes that they will be a bit more hygienic, but I doubt that it will do all that much good.