In all major Indian cities outbreaks of communal and inter-caste violence can occur. Government response can be in the form of imposing curfews. Political rallies and demonstrations are to be avoided, especially around election time. Don't travel out of major cities at night. Dress and behave according to local customs.
Dangerous undercurrents occur at several of India's beaches.
Avoid trekking on your own or in small groups. Team up if possible. Those in possession of even small quantities of drugs face sentences of at least 10 years of imprisonment. It's known for people to be drugged, then robbed. Travel by road is dangerous.