How to avoid getting ripped off

I’m traveling to Kolkata, Siliguri, Darjeeling and New Delhi next month. I’ve been brought up in Kolkata, studied in Delhi, and worked in Bangalore before moving overseas 6 years ago. I’m aware of haggling and bargaining when needed. However, my partner and my in-laws are traveling to India for the first time with me. They are from New Zealand and are completely relying on me for sightseeing and everything else. How can I avoid the typical “ripping off foreigners” when we are out and about? I’m introverted and avoid conflict or any confrontation. What’s the best way to deal with this?