Opening the "Displays" or "Sound" sections of System Preferences!
Opening System Preferences each time you want to change your Displays or Sound settings can be a pain, especially if you often hook up your Mac to an external display or you often want to change the sound inputs and outputs (like when recording a podcast or maybe for Skype). There is however a really quick way of getting to the right spot instantly. If you hold down "Option" and change the volume, it will open System Preferences in the Sound section. The same is true when you hold down "Option" and change the brightness. It will open the display settings. These two keyboard shortcuts can really speed things up.