You’re reading this and you think you have setup a 4 digit pass code and FindmyPhone app. If you haven’t do it now. If you have a mac and an iPad do the same.
But the above steps are not enough. Go to settings, general restrictions and enable it. Turn off deleting apps, turn off allow location changes, and accounts changes. Now if your phone is stolen out of your hand and not pass locked the thief cannot delete the FindmyPhone app. The thief cannot delete the account or any of your email accounts and cannot turn off location services.
Now go find the bastard!