Use it to navigate through each instance of the item you want to find. I'm sure you use Command-F to find items, such as words in a document or on a webpage. Or you can simply press Command-, (comma) to get to them in the fastest possible time. You can navigate to the Menu bar if you like and scroll through to access the Preferences. It works like this: You are working in an app, and you want to open the application’s Preferences. This is one of the least-known keyboard commands on a Mac, but it’s super useful. There’s also a keyboard shortcut - select an item (you can even use the Up and Down arrows to navigate to it in Finder view) and then press Command-Y.
To use QuickLook, select an item in Finder, press the Space bar and a preview will appear. A lot of people use QuickLook to preview items they're looking for.
