This is my little script to setup a new mac from scratch.
The best way to figure out what is going on, is probably to look at the setup.sh script itself. You're probably going to want to change things.
Run $ sh setup.sh, and the script will guide you through the rest.
Use the manualSetup.taskpaper list for the things that need to be set up manually. (Taskpaper lists can be copy-pasted into OmniFocus, you can use the Taskpaper app, or simply use it as a plain text file.)