Whenever you are working on something electrically make sure the breaker is off or the fuse is pulled. Just because the switch is turned off does not mean it is not getting power anymore. Safety is always an issue when it comes to electricity, so make sure it is completely off before you start.

When installing light fixtures or ceiling fans the harness and box that they are being placed on need to be completely secured to the ceiling or wall. You do not want it to fall and hurt someone, or worse fall and cause a wire because the wires came apart. Make sure the boxes and harnesses are approved for the area.

When installing switches and outlets in a bathroom it is better, and in some areas required, that you use a GFCI certified outlet and switch. These devices are designed with a breaker built in so that the power goes off if the device gets wet. This allows for a slimmer chance of electrocution in those wet rooms.