You need to take advantage of series of modes of traveling in India which are not available in most countries. "Rickshaw", "Trains-Travelling in India's trains is really different experience".
Enjoy those unique traditional foods like Samosa, Pakoras, Haleem, Pulses, Rotti especially Makki Rotti with Sarso Saag. Also, try Traditional sweets like Jalebi, Barfi, Kheer, Vermicellis and Khoya.
Visit the historical places where you are resising. India's Taj Mahal is one of the seven wonders of the world. Delhi city is full of historical places. Also, Mumbai city is India's most attractive modern day lifestyle presenting city.
Do not forget to practice their cultural traditions, Just watching them perform their culture won't be that much big fun.
Also visit What are the best places for couples in India?