The jewelry shops or gold shops as they are known there are the best and easiest places to change money. I have found them to be honest,just make sure you know the approximate rate. You can negotiate a little for larger amounts of money.
If you are in HanoiYou just go to Hang Bac street or Ha Trung street. They will do exchange for you with the bank rates. They accept almost currencies.
Use your bank debit card (Visa) to make ATM withdrawals, because that's the most comfortable.
Normally you can go to a travel agency, a bank or simply an ATM for currency exchange. We also recommend that you should pay attention to the charged fee, which depends on each particular place of exchange.