New smartphone, smartwatch, or other mobile device for holidays? Be sure to secure the old device's personal information.

Perform a backup of the old device

 Factory resets on Apple and Android.      Windows phones need more effort.

iOS:   Settings -> General -> Reset -> Erase All Content and Settings

Android:  Settings -> Privacy -> Factory Data Reset

If you are keeping your old phone number, the SIM card will be transferred to the new device. If not destroy it.