The article first discusses how to hibernate your computer (rather than putting it to “sleep”) saying this uses less power. If you use BitTorrent, download large files, or work remotely this might not be appealing but this article also discusses options such as setting your computer to shut down when the download is complete or using other programs like WinOFF (shuts down after set amount of time) or Wake-on-LAN’s (restart your computer remotely) Try Smart Sleep for MAC.
The second point in the article is on saving paper when printing, listing easy ideas like printing duplex, printing to PDF, preview before printing, and not just printing several copies of an email or Web page to share with others. Firefox offers a n extension Aardvark which helps you tweak your page to print only what you need and how you want it. The article also mentions GreenPrint (which I blogged about previously).
The third and forth points are on good energy use. Turn off any peripherals you don’t need at the time. Realize many peripherals draw power even when off if they are still plugged in the wall outlet, so either unplug, use a power strip and turn it off, or use a smart power strip (one that will monitor your PC’s power state and automatically shut down other peripherals). Also think about downloading a program such as LocalCooling (free!) to monitor and tweak your power usage.