Travelling alone is not really an issue in India as long as you keep your wits about you.
Rather than robbery the main things to be careful of are food poisoning and rabies. In some places such as Varanasi getting an upset stomach is pretty much unavoidable as the Ganges water will find itself into the food chain. Most chemists sell medication to clear this up so it's nothing to really worry about.
On the other hand pretty much anything with a back bone will be carrying rabies,...more »