Bootstrap your Raspberry Pi

Install Raspbian on a SD card

Download the latest Raspbian lite image from the download page.
Download and install Etcher.
Open Etcher and flash the OS image to an SD card.

Enable headless access

Mount the SD card on your computer
Put an empty file named ssh in the boot partition to enable ssh.

sudo touch /Volumes/boot/ssh

Edit config.txt

Mount the SD card on your computer
Open file for edit named config.txt in the boot partition.

vim /Volumes/boot/config.txt

Enable serial console (optional)

Add or edit the following line enable_uart=1
On Raspberry Pi 3 also add dtoverlay=pi3-disable-bt

Adjust gpu memory (optional)

Add or edit the following line gpu_mem=16
The minimum value is 16.
The maximum value is 192, 448, or 944, depending on whether you are using a 256MB, 512MB, or 1024+MB Pi.

Initial setup

Put the SD card into the Raspberry Pi and boot the device.
Log in with the default credentials (pi/raspberry).

Setup Passwordless SSH access

Copy your public key to the Raspberry Pi authorized_keys file

ssh-copy-id pi@raspberrypi.local

Add or edit the following line in /etc/ssh/sshd_config

PasswordAuthentication no

Change hostname

Change raspberrypi to your desired hostname in /etc/hostname and /etc/hosts

NEW_HOSTNAME=new-hostname
sudo sed -i "s/raspberrypi/$NEW_HOSTNAME/g" /etc/hostname
sudo sed -i "s/raspberrypi/$NEW_HOST/g" /etc/hosts