Many homeowners who are willing to do the work of changing a switch or replacing that old ceiling fan do not do the work for fear of getting shocked. It is much easier to follow protocols to avoid getting shocked when working with home electric than it is to do the actual work of those electrical projects needing done.
First and foremost is to identify the correct fuse or breaker at the service panel that disconnects the power to the circuit being worked on. Second is to not only shut off the power to the circuit but post a written notice on the service panel that the power is off because it is being worked on. This way a family member who thinks it is just a blown fuse or breaker will not restore power while dad is up on the ladder wiring up the new ceiling fan.
A word of caution all homeowners with questionable wiring should adhere to is to not rely on just a wall switch cutting the power to a circuit. In some homes with faulty wiring, the return side of circuits instead of the hot side of circuits may be what is cut at the switch. This means that current is still at the appliance such as a ceiling fan, but the circuit is not complete because the return path is what is being switched off.
There are small current detecting devices available for homeowners that will add another layer of proof that the current to a circuit is off. They operate while the circuit has a load on it such as a light being on or a motor running. When the power is cut at the service panel, the current detector will indicate that electricity is no longer flowing in the circuit. These devices do not require contact with bare wires or terminals to work and are better than relying on just watching for the appliance to switch off. After all, it may just be that a light bulb burned out instead of the correct breaker being shut off.