When working in any photo manipulation package, and especially when first starting out, it is very important to develop good habits. One habit you need to develop early is the use of shortcut keys instead of menu buttons. This will dramatically increase speed once you practice and get use to it.
To help in your quest for increased productivity here is a list of some of the best cheat sheets you can find for Photoshop, PS Lightroom, PS Elements, Aperture, and Gimp.
Adobe Photoshop CS4 Keyboard Shortcuts
Adobe Photoshop CS3 Keyboard Shortcuts
Photoshop Lasso Tool Cheatsheet
Photoshop Elements 7 For Dummies Cheet Sheet
Adobe Photoshop Lightroom Cheat Sheets
Photoshop Black and White Cheat Sheet
Photoshop Secret Shortcuts from Web Designer Wall
If you have any other cheat sheets you would like to share please leave a comment below.