6 Hacks for Mac you should know

1.  Tailor-made Finder: not everybody knows that the Finder can be customized. You can add buttons such as Delete, Connect to, Share, Quick Look and others by simply right-clicking the top of the Finder window and selecting Customize Toolbar. Afterwards, you can drag the additionals buttons you want to the toolbar (in the example below I've added Delete, Share and Quick Look).
   
   
   
2. Fast screenshots: I use a lot Skitch for this (see here for more details), but OS X offers a quick built-in way to take a snapshot of a selected portion of your screen, by pressing CMD/SHIFT/4. This allows you to copy and edit a screenshot while working on the wording of your post, for example.
3. Freaky Fast Start-Up: If you need to boot your Mac real quick to check out something like email, you can press down the Shift key while loading the OS, to get to a blank desktop. This is the so-called Safe Boot, which is the equivalent of Windows Safe Mode (check here for more details about it).   
   
4. Delete a file with a keyboard shortcut: Lots of Windows switchers may be frustrated because they can't delete a file from keyboard the same way as Windows (i.e. by pressing Delete). Well, I got good news for you: you can! You only have to press CMD/DELETE to get the same result. What's more, you can rename your file by pressing Enter.
   
   
   
   
5. Customize the default application for a certain file type: Sometimes you want to choose a different application than the default for a certain file type, because you need to use a specific program or because the default program configured by OS X isn't the proper application to open that file type (e.g. the default application for .rar files on my Mac is VLC, which is totally wrong). To do it, right-click a file having that specific extension and select Get Info (you can also open the latter window pressing down CMD+I). Afterwards, click Open With and select a different application for that file type. Click Change All and then Continue to confirm and apply your changes.   
   
   
6. Activate right click: OS X, out of the box, doesn't support the right click and, if you switch from Windows, you'll be probably a little confused by this. Luckily you can enable the right-click from System Preferences/Mouse, by checking Secondary click and then selecting Click on right side from the drop-down menu.