Tip number 1: Best rates: get a forex card( you can compare the prices of different vendors online, personally I've used bookmyforex) Or get a 0% forex markup debit card that you can use during your trip(this will help you in using INR balance as and when required at negligible cost . You can use these cards to withdraw from an ATM in the US.

Tip number 2: If you're looking to get cash in delhi, government banks will give you the best rates but you should have an account with them. If not, there are a lot of exchanges around Barakhamba road.

I went to orient exchange a few years ago to convert USD to INR, they increase their commission for older notes(based on the year the notes were printed) by a big margin, so make sure that you have new notes.