If you spend a lot of time in front of a screen working on print files, learning a few basic keyboard shortcuts can save you oodles of time. Using keyboard shortcuts can not only make you more productive, but it can also make you more efficient! The mantra is “work smarter, not harder!”
Many of the Adobe Photoshop key commands are intuitive, such as striking M to select the Marquis too, E for the eraser tool, or B for brushes. Some are a bit more obscure, such as striking V for the Arrow tool (well, maybe the V could be considered an arrowhead?), or J for the red-eye tool.
Watch this short video from About.com to learn more.