Must do's
Hire a driver who has a large 4x4. You don't want to drive there or use public transport. Labour is cheap, so is petrol and hiring a car and a driver will be an expense but worth it over losing your life. I assume your brother is marrying someone from there so get a local family friend of the bride to set this up for you so you don't get scammed.
Don't take advice from random people. They are trying to scam you most likely.
Don't buy anything expensive yourself get a local family friend to go into the shop and haggle for you whilst you stay out of sight of the shop. Once they know it's for a foreigner the price multiplies by 10. So it's best you get someone else to buy stuff for you and you let them know what you want outwith eyesight of the shop and obviously don't make it obvious you are together.
Don't drink tap water. Bottled water from a reputable source only. You will likely need to go to a large store and just buy 4 cases of the stuff on your first day. Use that water for everything. Cleaning your teeth, making tea, cooking, anything you will be consuming. Ask for no ice in all drinks as that will be tap water. I have 2 relatives in india who have both needed kidney transplants due to tap water. They got it tested and results were bad so they dug a deeper well and that was also bad, this is after they had been boiling it then filtering it too. SO I wouldn't go near the stuff.
Only eat in reputable places. Take loads of immodium with you as well as electrolytes. You will get the runs and you will need a lot of both.
Other than that stay safe. You will be a target for all the low lifes, beggars will harass you constantly, i've had them chase my taxi for several blocks, i've had others harass me at a market for nigh on 6 hours the full day i was there. Lots of lepers and the poor is so vast as soon as you give money to one another 10 will see it and pop up requesting some too. It's an endless cycle.
Go watch some Karl Rock videos, he does videos on India for tourists
India is 20 times the size of the UK. The place he is going to is in the south where people are more darker skinned and shorter. They will likely speak their own dialect too which Karl Rock wouldn't understand. He only speaks the national language.
His videos are not for tourists at all but for anyone and more educational and to make him money. The fact a lot of indians watch his videos for instance.