I couldn't tell you, since this will be my first time, too. I was wondering the same thing. What if I find some wonderful thing that I really need, and I've run out of cash? I would hope that I could use my credit card if absolutely necessary.
But I'm guessing that cash is the most reliable option...
Do like me the first year, don't bring enough money.
Then you get to enjoy the three hour line in town by the ATM and miss some of the bands
Just bring a bunch of cash if it's your first year, you'll most likely find shitloads of stuff you wanna bring back home, I know I did.