Here’s a small and potentially useless tip. There might, however, be some situations in which this is handy.
As you have likely noticed, Mac keyboards come with volume control keys (on the F10, F11, and F12 keys) and keys to control screen brightness and keyboard illumination (on MacBooks).
When adjusting volume, for example, using these keys you get 16 volume levels or jumps. If you would like more precise control of the volume (using the keyboard) you can hold down Option and Shift whilst pushing the volume Up or Down keys. This will give you the same precise volume control you have in the System Preferences > Sound panel, and in the menubar Sound Volume control.
The same thing applies to adjusting of keyboard illumination (on MacBooks) and screen brightness.