Take all precautions to drink clean water and eat only hot food. Do not display your money or expensive jewelry in public. Watch out for pickpockets and petty thieves. You may need to leave your shoes outside some of the monuments. Get used to crowds! Photography may be prohibited at monuments, temples, etc. People in India are very religious and some of the traditions have been around for millenniums. Respect the culture and their beliefs even though yours may be very different.
