How do you manage your money?

The currency of India is very strictly controlled. You cannot take currency into the country, or bring it out. This means that one of your first jobs is going to be to change some cash.
The rate of exchange is set every day, and you should not find much difference between changing money at the airport, a bank, your hotel or a reputable money exchange, although the smaller ones in the most popular tourist areas are the worst and can rip you off. If you need to change money at your hotel give plenty of notice. Only the larger hotels will do this, and always make sure that they will accept creit cards- some don't. Make sure you have plenty of time before trying to change money at a bank. Most will try to send you elsewhere, and there is usually only one branch of a bank per town which will do this. Be prepared to fill in lots of forms, to watch others filling in lots of forms and to watch the man with a clipboard who appears everywhere to delay the simplest transaction. You will need your passport to get cash wherever you are.
At one time travellers cheques were the safest way of carrying money, and these still work in the larger hotels and banks. Now there are ATM machines in most towns, although never as many as you see at home.
It is porbably best not to rely on a particular machine at a particular time. The electricity supply and poor network connections can mean that your transaction will be very slow, not happen at all or get lost in space, leaving  you wondering whether your money has joined the transaction in a wormhole in the ether.
You need to plan ahead, take care of cash and check whether your payment method is acceptable well in advance if you do not want to spend your holiday chasing cash.