You can preview your Screen Saver choices right there in the System Preferences app. It's much quicker to do it this way.
Preview your Mac screen saver choices
Hold Command key to see file path in Mac’s Spotlight
Spotlight is great, it finds stuff for you. But when you want to know where the things it found are, it falls short. Unless you use the Command key!
Essential Mac Keyboard Shortcuts: Command-A for “Select All”
The 60 seconds it takes to learn this shortcut will be paid back thousands of times. You have to know Command-A for Select All. Practice!
Essential Mac Keyboard Shortcuts: Use Spacebar to pause/resume audio and video in iTunes and YouTube
Use the space bar to quickly pause audio (or video) in a variety of Mac apps. Tap it again to start it again. Very handy.
Stuff the cat did: toggled VoiceOver so my Mac started talking
Your Mac can talk to you, telling you which button you're about to click, which menus are showing, and so on. Very handy if you can't see well, but very surprising to have it turned on by itself. Or by the cat.
Option-drag to resize Mac windows and graphic objects in two directions, keeping the center fixed
Resize Finder windows and graphic objects from the center by holding the Option key while you drag an edge or corner. Grow the item while keeping the item's center fixed.
Command-click a window’s title to show the document’s location
Here's how to know the location of an open document, all with a simple click. Actually, all with a simple Command-click. It's a great feature.
Speed up your older MacBook Pro with a Solid State Drive (SSD)
Some Apple laptops are easy to open, making it easy to upgrade to solide state drives. You'll get big performance improvements with an SSD.
Hold the Command key down to drag things around in Mac app toolbars
Many Mac apps have toolbars-- Mail, Safari, Pages, Numbers, Keynote, and many more. The tools on such toolbars can be rearranged via Command-drag.
On a Mac, Control-click = Right-click
The Control-click technique opens up all sorts of options for you, all of them very quick and easy to access. You don't need a two-button mouse to right-click!