When did you last dust your lightbulbs? Clean lightbulbs deliver a lot more light.
When did you last clean the dust and dead bugs from your ceiling fixtures? Lightbulbs in clean fixtures deliver a lot more light, too.
Do you have multiple small lightbulbs or one big lightbulb? One big lightbulbs delivers the same amount of light more efficiently than multiple smaller bulbs with the same wattage.
Do you leave your lights on for security purposes? Having your lights on a timer gives you the security you are looking for without spending so much on electricity.
Note: these tips work equally well regardless of what kind of lightbulb you are using. Of course, by switching to an compact fluorescent light (CFL) bulb, you can save 2/3 on your lighting bill ... but then you already knew that, right?