Well, as most people should know that in case you lost your phone, you can use Android Device Manager to locate it and normally, it is on by default, but this is for those who turned it off or somehow the setting has been off.
With most phones, it is normally turned on when you were setting up your phone and signing into Google Accounts. To check or or turn on Android Device Manager, here is a step-by-step instruction:
1. Go to Google Settings (either an app or from your phone's setting menu by scrolling down to "Google")
2. Within the Google Settings, go to Security.
3. Make sure Remote locate this device and Allow remote lock and erase is switched on under Android Device Manager
4. Make sure under your Settings, Location (GPS) Access needs to be on
5. That's pretty much it. Go to: www.android.com/devicemanager and try locating your device by logging into your account and make it ring or whatever you want to make sure it works.
Enjoy and don't lose your phone . I know it's a simple tip, but some new user to Android might not know about it or use other manufacturer apps (e.g., Samsung, etc.), when Google Android Device Manager have the same functionality and is already tied into your account.