Modifier keys

Here is how I like to set up my modifier keys on MacOS (System settings > Keyboard > Keyboard Shortcuts > Modifier Keys): Screenshot of my MacOS modifier keys configuration

Automator Quick Actions

To create custom actions in MacOS, open Automator and create a Quick Action (see examples below). Once your Quick Action is created, you can associate it with a keyboard shortcut in System settings > Keyboard > Keyboard Shortcuts > Services > General.

Quick actions are saved in ~/Library/Services. To go to ~/Library in Finder, hold down the Option key while clicking on the "Go" item in the menu bar at the top of the screen.

Copy text to clip board

I use this type of Quick Action with my email addresses so that I never mistype them: Screenshot of my MacOS Automator Quick Action for copying text to the clip board

Screenshot of my MacOS Automator Quick Action for copying text to the clip board

Edit file in terminal-based text editor

This Quick Action allows me to easily edit a text file from Finder (this example uses Emacs):

Screenshot of my MacOS Automator Quick Action for opening files in Emacs from Finder

You can find it in Finder's Quick Actions:

By right-clicking on one or more files
In the bottom right part of the Finder window when using the "columns" view