Google's simple VR platform can be used anywhere and everywhere, but there are a few things you should do for an optimal experience.
One of the great things about Google Cardboard is how portable it is. While not every version of Cardboard is fully collapsible, even when fully set up these accessories don't take up a lot of space, and for the most part you can just pop your smartphone in and get up and running. It's the perfect platform for quick VR experiences, and is simple enough that you can pass things around to the group and not have to worry about a learning curve for use — which makes comparing it to full immersion platforms like the HTC Vive-powered Steam VR platform easy.
Here's a quick intro to using Cardboard, as well as a few tips for getting the most out of the platform.
All you really need to get started with Google Cardboard is the accessory and your phone. Once you've installed the Cardboard app you're walked through a simple set up process, which varied depending on what Cardboard accessory you are using. The app will ask you to scan the QR code near the orange Works with Cardboard sticker on your accessory if you're using something made by an official Cardboard partner, and doing so will calibrate any apps using the Cardboard SDK to match the lens type and fit in your box. You can always use the default Cardboard settings, but the sticker calibration method ensures you're getting the whole picture through your accessory.
Once you've got the Cardboard app running and held to your face, you can choose what apps you want to use and jump from one virtual environment to another. Outside of the official Cardboard app, there are tons of apps that support this same split-screen visual format and work great within Cardboard. Many of these experiences are highly visual, or include some simple and addictive gameplay mechanic, but nearly all of them are made better with the addition of a decent set of headphones or earbuds. Audio completes the immersion, and while your phone's audio jack is exposed through most Cardboard variants not all of them give you convenient access to your volume rocker, so set your audio before getting yourself ready to play.
And that's it, you now have everything you need to be that guy on the bus, that girl with the awesome VR thing over there, or the person who quietly enjoys this setup at home when no one is looking.