CTRL-C / CTRL-V: Let's start off with the most basic basics: CTRL-C copies whatever you have selected in your program and CTRL-V pastes it back in. Simple as that.
ALT-PRINTSCREEN: Saves a screenshot of your current computer screen into your clipboard so the next time you hit CTRL-V you'll paste a spitting image of your screen.
CTRL-Z / CTRL-Y: These keyboard combinations allow you to undo and redo your last action(s) on the computer. Useful for those DOH moments when you accidentally type over something important or make a mistake and want to go back a few iterations. As long as you don't interrupt, you can keep going backwards and forwards for quite a bit.
CTRL-S: Instead of trudging your mouse all the way up to the file menu and selecting the menu option to save your file, you can just hit CTRL-S to do the same. It's so quick and easy you should actually make it a habit to constantly hit CTRL-S to save your work.
CTRL-N: You might be well aware that in your web browser this key combination will bring up a new window, but did you know this works the same in Windows Explorer? Hit CTRL-N to open up a new instance of your file system browser in the same spot you're in now. In Outlook this combination opens up a new e-mail message.
WINDOWS-E: Opens up a copy of Windows Explorer.
WINDOWS-D / WINDOWS-M: Minimizes all open windows and shows your desktop. Quick for hiding that game you're playing instead of working when the boss pops his head into the office. Or for other unnamed activities.
WINDOWS-R: Opens up the run dialog box for quick access to the command line.
CTRL-ALT-DEL: It's not that this command itself is an advanced combination, but opening up the task manager other than for a reboot is usually for those who understand how to find and kill open processes, etc.
WINDOWS-L: If you're stepping away from your computer and want to keep your system safeguarded from Facebook bombers, simply hit WINDOWS-L to lock your system and bring up the Windows login screen.
MORE WINDOWS & OS XKEYBOARD SHORTCUTS ON APARTMENT THERAPY:
• Windows Keyboard Shortcuts
• CheatSheet: The Instant Refresher Course For Keyboard Shortcuts
• Keyboard Shortcut Cheat Sheets That Add to Your Decor
• How to Operate Your Computer Without a Mouse
• Mac OS X Keyboard Shortcuts to Save Time
• How to... Customize Your Own Mac Keyboard Shortcuts