When installing Emacs via
$ brew cask install emacs
it automatically installs emacsclient, but this needs to be launched via the terminal. When running the Emacs.app from Applications it will launch a new instance of emacs every time. Most of the time when I want to quickly edit something I tend to prefer to launch emacsclient to create a new window or frame in the existing running instance. Since I launch almost all my applications via Spotlight the simple way to achieve this is to create a script with the .command and use this instead.
$ cat ec.command #!/bin/bash EMACSCLIENT=/usr/local/bin/emacsclient $EMACSCLIENT -n -c -a '' $*
With this in place configure the script to be run via the terminal of your choice, in my case iTerm, by right clicking on the file and Get Info.
Thats it now Spotlight will execute the script when typing ec and hitting Enter on the top hit, assuming it is indexed.