It is important to set up your banking before you leave home. The two main cards you will be bringing on your trip is a Debit Card and a Credit Card. You will need to contact your bank and give them the time-frame of your travels and the countries you expect to visit to ensure they will not put a hold on your account. I would also do some research and see if you bank has any affiliates in the countries you're visiting, these will usually void the overseas fee's incurred.
If you plan on ordering a new card for your trip, make sure to do it two full business weeks in advance or you may have to pay a rush fee in order to get it on time.
Debit Card : Unlike in the US or Australia, Europe has many places that only take cash. Most places that do accept credit cards will charge a processing fee. It is important that you have a checking account set up in order to pull out cash whenever needed.
A debit card used while traveling MUST have a 4 digit pass-code. Any additional characters will not work on their cash machines and cause the transaction to fail.
Given that you will be using different currencies throughout your travels, you should make sure that your new debit card does not charge a fee for currency conversions. Some banks will charge upwards of 5% of your total transaction just to withdraw in the new currency.
See if you can also find a debit card that does not charge fee's to pull out money from different banks cash machines. This will save you a lot of money in the long run, every $5 adds up!
Credit Cards : These will follow the same rules as the debit card, except one additional item. Your credit card must have an international chip in it in order for it to work, not just a swiping strip.
I would also advise you to find a card that rewards you with points throughout your travel, might as well get something back for all the money you will be spending!