You may need to open System Preferences from time to time to adjust network settings, change user account options, or some other task. If you don't keep System Preferences in your Dock, you can set a keyboard shortcut to make it launch.
To create the shortcut, open the Keyboard & Mouse System Preferences panel, click on the Keyboard Shortcuts tab, then click the plus (+) sign. In the dialog that appears, leave Applications set to All Applications, set the Menu Title to System Preferences... (that's an ellipsis--use the Option-; key combo--and not three sequential periods), and enter your desired shortcut in the Keyboard Shortcut box.
Since the standard keyboard shortcut for preferences in any application is Command-, (Command-comma), you might want to use Command-Option- (Command-Option-dash) or something similar. After you set the keyboard shortcut, you'll need to log out and log in again, or restart your Mac, for it to be available.
What's interesting to note is that you can set keyboard shortcuts in this manner to any menu command in the Apple menu. For instance, if you move your dock around somewhat regularly, you can assign keyboard shortcuts for the Position on Left/Right/Bottom menu items. Or assign a shortcut to Software Update, to make it easy to repeatedly check for new updates on a day when you're expecting one.
"Launch System Preferences With a Keyboard Shortcut" Comments