The next time you end up in an Open or Save dialog window, try out a few of these helpful keyboard shortcuts to make navigating around the dialog and filesystem much faster.
Command+D
Selects Desktop as the destination.
Command+Shift+H
Sets the Home directory as the destination.
Command+Shift+A
Sets Applications directory as the destination.
Command+Shift+.
Toggle invisible items.
Command+Shift+G
Bring up Go To Folder window.
Command+R
Open the selected item in the Finder.
Command+F
Move the cursor to the Find field.
Command+.
Close the Open/Save dialog window.
Spacebar
View the selected item in Quick Look.
Tab
Tab key auto-completes paths and file names from the aforementioned Go To Folder window.
When you use the volume controls on a Mac to increase or decrease the sound coming from your speakers, those levels increment in whole steps on a scale from one to ten, press the up volume button once, for example, and the volume goes up one step out of ten. However…
If you hold down Shift and Option (Alt) before pressing the volume keys on your keyboard, you could adjust the volume in quarter-steps instead of whole ones. In addition to using this Shift and Option (Alt) combination to control the volume more finely, you can also use it when you adjust the brightness on your Mac. Press Shift and Option (Alt), then press one of the brightness keys on a Mac keyboard, and you'll notice that the brightness changes in quarter-steps. This is nice if you find your display is just a bit too bright or too dim.
When you get ready to sell or give away your Mac, there are some steps you should take. You'll want to back up your computer, disable some features and services, and erase the hard drive.
Moving to a new Mac? Learn how to move your files to your new Mac. Do this before you erase the hard drive or follow any other steps.
• Create a backup. Be sure you have an up-to-date backup of your important files and data. Learn how to back up your data in OS X.
• Sign out of iTunes. Open iTunes. From the menu bar at the top of your computer screen or at the top of the iTunes window, choose Account > Authorizations > Deauthorize This Computer. When prompted, enter your Apple ID and password. Then click Deauthorize. Learn more about deauthorizing your computer using iTunes, including how to deauthorize all the computers you've used with your iTunes account.
• Sign out of iCloud. If you use Find My Mac or other iCloud features on your Mac, you should first archive or make copies of your iCloud data. After that, choose Apple Menu > System Preferences, click iCloud, and then deselect the Find My Mac checkbox. Finally, sign out of iCloud. In System Preferences, click iCloud, and then click the Sign Out button. When you sign out of iCloud, you're asked whether you want to remove iCloud data from your Mac. Your iCloud data will remain on any other devices that are using the same Apple ID.
• Sign out of iMessage. If you're using OS X Mountain Lion or later, sign out of iMessage. In the Messages app, choose Preferences > Accounts. Select your iMessage account, then click Sign Out.
• Erase and reinstall OS X. To reformat your hard drive and reinstall OS X, follow these instructions. After you reformat your hard drive and reinstall OS X, the computer restarts to a Welcome screen and asks you to choose a country or region. If you want to leave the Mac in an out-of-box state, don't continue with the setup of your system. Instead, press Command-Q to shut down the Mac. When the new owner turns on the Mac, the Setup Assistant will guide them through the setup process.
Do you use an external drive or a flash drive to store some of your data? Then you might consider encrypting it. It's a bummer to lose a piece of equipment or have it stolen, but what'd take that from bummer to nightmare is knowing that someone may have access to, say, your private financial information.
Here's all you need to do to encrypt the drive and protect it with a password:
• Connect any external drive to the Mac
• Right-click on the external drives name in the Finder and choose "Encrypt DiskName…”
• Set and confirm a password, then set a reasonable password hint, followed by clicking the "Encrypt" button
Do not forget the password or you will lose access to the data on the drive!
• Wait while the encryption takes place
The encryption process can be very quick for smaller drives like USB keys and SD cards, but can take quite a while for large external hard drives used for backups or personal data. Be prepared to wait a bit for anything larger than a few GB in size, as the general encryption-to-GB time ratio seems to be about 1 GB per minute.
Once the drive has finished encrypting and is disconnected, a password will be required before the data can be accessed from the Mac. To maintain the password protection, be sure to uncheck saving the password to the Keychain when asked.

Did you know that OS X lets you rename a file directly from the application it's opened within? This feature is supported in most bundled Apple applications, including TextEdit, Pages, Preview, and others.
• Hover over the title bar
• Click the filename to pull down a menu, enter the new name and hit the return key to save the files name change
The file extension remains consistent with the files format, and unlike renaming things in the Finder you can't accidentally change the file extension too. The usual method of renaming files through Finder is still around, but if you're saving files directly to iCloud this is likely the preferential method.