I have updated my Installation Guide for OctoPrint 1.4.0 under Python 3. This is the setup I use to test different versions of OctoPrint (stable, dev, my own, …)
It is rather complete, and includes the installation of Raspbian itself, multiple python virtual environments using
virtualenv , using Supervisor to manage OctoPrint instances, NGINX as a reverse proxy and also as a front end to display a page with all the instances.
The guide is available here: