Is there a preferred method for placing a switch cable to a device? Is it better to put the switch circuit on the POWER side of the device or on the GROUND side of the device?

Putting a switch on the ground wire (green) would not allow you to turn it on/off. If you meant the white wire, that is the neutral, not a ground. You place your switch on the black (hot) wire. That way there is absolutely nothing hot on the device until the witch is closed.