One of the most helpful and time saving tips I can give new computer users is to learn how to use keyboard shortcuts. Mastering even just a few common shortcuts means no more digging through menu’s or right clicking to find the desired function. For instance, if you want to show the desktop, just press the F11 key; to copy and paste selected text use ⌘ + C and ⌘ + V; or if you want to open the Applications folder use ⇧ + ⌘ + A. So much time can be saved with keyboard shortcuts, and if you dig into the System Preferences, you can even create your own shortcuts. Here are two helpful posts from Macmost.com regarding shortcuts for Lion and Mountain Lion. Each link also contains a handy list of keyboard shortcuts that you can print and place on your desk as a reference!
Mountain Lion Shortcuts