I always wore a light material trousers/l/s shirts/ long skirts when out and about in the towns and cities, but on the beaches, the usual beach stuff.
I would throw on a cover up to go from beach to cafe/bar.
I went 7 years ago with another girl- we were 27- and we got a fair amount of male attention anyway. I also wore a hat/headscarf, tucked my long hair up.
I think if you wear shorts/vest etc in non beachy areas you will stick out like a real sore thumb and a total tourist, and IMO I think it shows a lack of respect.
I went to Mumbai, Delhi, Goa, Kerela.
It is STUNNING and if you are open to it, can fill you with total joy. India, really changed my perspective on life, and I LOVED it. Was there for 3m.
Eat what other people are eating, eat hot fresh food, stay away from salad! Street stalls where you can see what is going on is not only safe, but delicious and cheap.
Change money at the airport, do not accept any ones help in finding you a place to change money. Give sweets, food, milk, cans of drink to beggar children- not money, they don't get to keep it.
Agree prices with cabbies BEFORE you get in the cab.
take citronella candles with you, take spray too.