I wrote a blog on Trulia about how going green can cost a seller money, check it out.
Sorry to disagree, the very worst thing a seller can do is to stall those energy saver bulbs while the property is being shown. Afterward, go for it. But those bulbs throw the very worst light and take forever to get as bright as they can.
The big energy savers are replacing the windows, siding, exterior doors. If the furnace is not ready to be replaced, make sure you have had it properly serviced along with the central air conditioning. Have copies of those repair records on hand to show the buyer.
Also, a property with trees and natural shade is a real energy saver in the summer time. Consider installing a solar heating system for your pool if you need to warm it up.
More than 3 I know, but it's a start.
Have a great day!