I'm off to the USA for a week and as I'm on Vodafone, who don't do Roaming passes for the US, I've been advised to get a data sim. I don't know anything about them though. It looks like they're available on amazon, but do I just buy one and put it into my phone when I land? Is there anything I need to be checking for? The data would be really handy for Google Maps.
I only have a few days before I leave, please help!