Most important configuration on a Mac
One of the most important things you can do on a mac is remap caps lock to control. Sure, I am a little over zealous about this topic, but I really feel that this can make a huge diffrence to people who use modifier keys alot. And if you use a Mac properly one of the first things you should set out to learn are the keyboard shortcuts to perform you commmon tasks.
Open system prefrences and click on Keyboard.
Click on the ‘Modifier Keys’ button.
On the first dropdown, the one for Caps Lock
Set it to be Control.
Why am I so over enthusiastic about this? Mostly because I use to get wrist pain in my left hand and nosiced I was straining to contort my hand to press common keys like <Control>-A, which is got to beginning of line on OS-X (and in emacs/terminal/anywhere awesome). Suddenly this became easy and quick. Way better faster and easier on my wrist.
Added bonus (as if I could pick just one added bonus): Launch Bar uses <Control>-J and <Control>-K to act as up and down. This alone is one producitivity hack that speeds up many common tasks for me.
Give it a shot, make is muscle memory and you won’t want to go back.