One very important tip I haven't seen (or missed) for first timers to Europe: your atm pin needs to be 4 digits in Europe. The 5 or 6 digit pins that a lot of people have in the US often won't work. Also, most keypads have only numbers, not letters, so you can't just memorize a word.

Lastly, I've never had to use them, but I always get a couple hundred dollars in travelers checks just in case. I've had times when an atm machine in Europe just wouldn't give me money that day, but did work for my partner (even though we're with the same bank - strange). It's kind of scary to contemplate not being able to access money when you need it, so I always get the traveler's checks as insurance. Then again, I also purposely do not know the pins to my credit cards, so I only have the one card available to get cash. Just do what makes you most comfortable.

Have a great trip!