Lot of factors lot of questions lots of advise, but they all depend on each other.
Which cities is she heading to? How long is she gonna be here for? What is the purpose of the visit? Does she already know a foreigner who has been living in India? Is this a backpackers trip or a high end agency planned tour?
If she's travelling in a group she should have absolutely no worries at all. If she's going to Bombay(Mumbai for assholes) then she can travel alone and drink all night long without any concerns. Delhi is the only place i'd be worried about but only is she's into exploring mode at the wrong time at the wrong place.
Hope that helps