Two differents ways to get cash in India
Note that Indian banks charge 100-150 rupees (approx 3 USD.) For each transaction you make, you need to add to that the fees from your bank. You can withdraw only 10,000 rupees at a time (option to renew the process several times). The best, if possible, is to bring at least two bank cards to not find yourself in a difficult situation if one of thetwo cards do not work.
Also remember to check your withdrawal limits and payment by credit card before you leave and negotiate your withdrawal fees with your bank (to pay a fixed amount per month for example).
It happens quite often that Visa or Mastercard block your card. Just call their customer service to unlock.
Two exchange offices located in M Block Market, Greater Kailash 1 will offer you a very reasonable and favorable exchange rates, generally the exchange rate of the day.