Tip: Hide Windows
One thing I see a lot of when working with clients on their machines is that they'll move or close windows when they want to get to their desktop. There's a much easier and faster way: Command-H (think H for Hide). This will hide all of the open windows associated with whatever application you're currently in. Alternatively, you can click the Finder icon in the Dock to switch to the Finder and then hit Command-Option-H. That will hide everything other than the current application, in this instance the Finder.