Do not open your hotel rooms without the safety latch.
Some parts of India are still traditional and conservative. It is therefore advisable to dress appropriately.
Dress codes for religious places can include covering your head, being barefoot etc.
Being from a different country, chances are that you might attract some attention, especially in the smaller towns.
It is advisable to use clean toilets available in places such as hotels and restaurants.
Drink only bottled water. In restaurants insist that they bring a sealed bottle to your table.
Eat non-veg only in good restaurants.