Link Your Google Account
If you linked your Google Account with your phone, if you lose your phone, you can go to the Google Android Device Manager and 1) lock your phone and 2) locate it on Google Maps so you can get it. If necessary, you can also erase the data on the phone as well.
Enable USB Debugging in Developer Mode
USB debugging allows you to transfer data between a computer and your phone. It’s handy if you broke your phone’s screen or otherwise can’t get into your phone to back up data. Many backup utilities only work with USB debugging enabled.
Back Up All Data including App Data to Google Drive
If you back up all your data such as photos and WhatsApp messages to Google Drive, then if you lose your phone, you’ll still be able to access your data.
Install a app like WheresMyDroid to be able to control your phone from other another phone or computer. This can be handy when you want to unlock your phone, make your phone ring, etc.