Instructions
Place the Wii on a surface or structure where the air vents on the back of the console will not become obstructed. For instance, avoid putting the Wii in a tightly enclosed space or on thick carpet.
Turn off the Wii after each use, either by pressing the "Power" button on the front of the console or the same button on a Wii remote.
Check the air vents periodically and clear them of dust or any other foreign material.
Store the Wii in a place that is not humid when not using it.