• grab the last release from https://octopi.octoprint.org/latest
  

• Unzip the image and install the contained .img file to an SD card using Etcher
  

Do not at any point format the SD from your Operating System, even if prompted to do so - that will break it and you’ll have to start over.

• Configure your WiFi connection by editing octopi-wpa-supplicant.txt on the root of the flashed card when using it like a thumb drive.
  

Important: Do not use WordPad (Windows) or TextEdit (MacOS X) for this, those editors are known to mangle the file, making configuration fail. Use something like Notepad++, Atom or VSCode instead or at the very least heed the warnings in the file.

• Boot the Pi from the card.
  

• Log into your Pi via SSH

it is located at http://octopi.local if your computer supports bonjour, or the IP address assigned by your router. Default username is pi, default password is raspberry

passwd
adduser thisisausername
usermod -aG sudo thisisausername
su - thisisausername
sudo bash

this will allow you to change the password to the user pi, so someone can't just try the default login and access your octopi server. it will also add another user and pw combo of your choice, so if you want, you can later remove pi as a user completely, or restrict it to the point where it cannot access anything critical.

apt-get update
raspi-config
update tool
expand SD card
enable camera
enable ssh server
reboot

this allows you to use the full size of the sd card, turns on the camera for monitoring prints, and enables ssh

nano /etc/dhcpcd.conf
interface eth0
static ip_address=192.168.1.48/24
static routers=192.168.1.1
static domain_name_servers=192.168.1.33
interface wlan0
static ip_address=192.168.1.xxx/24
static routers=192.168.1.1
static domain_name_servers=192.168.1.33\\

in the above example, we're editing the dhcpcd.conf to give the octopi static IPs. you really only need one or the other, depending on if you are hard-wiring or running your pi wireless (more common).