Traveling overseas with iPhone 5s?

I'm very paranoid that I'll rack up a huge cell bill while overseas. The only thing I need to do is turn off cellular data?

Turning off the data connection will stop any apps or the operating system itself from downloading data, so you wouldn't have to pay any data charges. However, you should still find out what the score is with call charges so that you know what's affordable. With some contracts you have to pay to answer calls when abroad, so make sure you know about any sneaky charges like that too.

Put it on Airplane Mode & leave it there until you come back. You could turn on Wi-Fi after it is enabled to at least use that.