Buy good quality electrical cords and avoid overloading circuits to prevent electrical fires. Keep a fire extinguisher in the kitchen (and a fire blanket for fat fires) and the bedroom area, and make sure everyone knows how to use them (don't forget their maintenance). Please don't forget your smoke detectors and the gas detector if using a gas cooker.
It is recommended to turn off the wall switches and the AC when not in use because of power surges and brown outs.
For TV's and computers, a UPS is strongly recommended whilst a voltage regulator is recommended for the refrigerator.
It is always useful to keep candles, matches, flashlights and batteries at hand.