A way to save energy in the household is to replace the incandescent light bulbs with florescent light bulbs throughout the household.  Florescent light bulbs have the same candle power (illumination) as incandescent; but, using less wattage.  For example, an 11 watt florescent bulb will illuminate the same as a 40 watt incandescent or a 23 watt florescent will illuminate the same as a 120 watt incandescent.  With household lighting averaging around 20% of the electric bill, the savings will be approximately 70% of that 20%. 

While there is a large savings in electrical use, there are a couple of factors to consider before switching.  One is that florescent bulbs cost more per bulb than incandescent bulbs; but, they can can have a longer life span.  The reason the florescent "can" last longer rather than "do" last longer is that the florescent time span is related to the number of times the bulb is switched on and off.  If the bulb is switched on and off infrequently, the bulb will last longer; however, the more frequent the bulb is switched on and off, the shorter the life span of that bulb. 

Another factor that needs considering is that florescent bulbs build up to illumination slower than the incandescent counter parts which means that the light will not be at its brightest at switch on time.  One will have to get use to not having the immediate brightness.  A review of the ratings can be found at rating lightbulbs.