Skip the "Are you sure?" dialog when emptying the Trash by holding the Option key. Also helps when something won't delete. Try it!
Mac Option Key tip #08: Option-Empty Trash
Mac Option Key tip #07: Option-Click to Download in Safari and Chrome
Trying to download a PDF form in Safari or Chrome? Hold the Option key as you click the link and the document goes to your downloads folder.
Mac Option Key tip #06: Option-Drag to Duplicate
The Option-Drag technique works all over the place. It's one of the handiest Mac things to know. It lets you make copies of things, rather than move them.
Mac Option Key tip #05: Rotate the Other Direction
Rotate pictures 90 degrees counter-clockwise in iPhoto, Photos, and Preview. If you want to rotate the other direction, hold the Option key.
Mac Option Key tip #04: Reveal a Contact’s Groups
The Mac's Contacts app reveals the Groups a contact is in, at the press of a key. Of course it's the Option key. This will help you one day.
Mac Option Key tip #03: Close All Finder Windows
Close all of your open Finder windows with a keystroke. You know about Command-W; try adding the Option key. Or, Option-click a Close button.
Mac Option Key tip #02: the Battery Status Menu
Hold the Option key while clicking on the Battery Status menu on your Mac laptop and find out whether your battery is in good shape or not.
Mac Option Key tip #01: the WiFi Menu
Hold the Option key, then click on the WiFi menu to see some interesting stuff about your network. Handy for trouble-shooting. Try it!
Mac Option Key tip #12: Open your Library folder
Your user "Library" folder is really important-- so important that Apple hides it. Here's how you can find it and open it up.
Mac Option Key tip #11: Delete a Messages conversation with one click
Cut your work in half in the Mac OS Messages app. Deleting conversations used to be click-the-x, wait for a box, then click Delete. Now it's one click.