Cell phone activation! Make sure you contact your cell phone provider to make sure they activate your phone for the countries you’re visiting (assuming that you have a world phone) and that you pick the right voice or data plan. Even with the right plan text messaging can still be expensive. Do not use your cell phone on a cruise ship! They add on high charges per minute.
When I went to Italy, I didn’t even turn my phone on. Just searching for a network would suck up a lot of my battery.