I am a big fan of Two Factor Authentication. If you are not familiar with two factor authentication, there is a good explanation here. I have enabled Two Factor authentication pretty much on any account I have that supports it.
Many Two Factor implementations use the Google Authenticator app to provide the authentication code. Setting up the authenticator is easy, you generally scan a QR code, and then enter the code to confirm the setup.
One of the difficulties when using Two Factor authentication is setting up the Authenticator app on a new or additional device. When you initially set up Two Factor authentication you are presented with a QR Code that is scanned by the app to automatically configure the account. Typically to set up another device you have to invalidate the original configuration, and sometimes even disable and then re-enable Two Factor Authentication altogether.
Recently listening to an episode of This Week in Google they shared a tip so simple I don’t know why I never thought of it. When you first enable Two Factor authentication for a given account download the QR Code image and save it somewhere securely. Since I use Lastpass as a password manager I create a secure note which allows me to securely upload and save the QR code image. Configuring the Authenticator App on an additional or new device is as simple as opening up the secure note and scanning the bar code.