raspberry pi 2 with Octopi (raspbian 8 jessie)
printer: Samsung ML-2510
Install and configure CUPS
I won't go over installation of CUPS, this is well documented and will be dependent on your printers. I suggest making your raspberry pi's IP static, saves a bit of headaches from the CUPS server configuration.
Not sure which one is the one I needed, but these install drivers for Samsung and others.
sudo apt install splix sudo apt isntall printer-driver-splix
Using the correct drivers is important. I tried using Samsung ML-2550 drivers but when google cloud print tried to print it would spin up but not print, and CUPS would think the print was successful. Switched to Samsung ML-2510 and it prints properly.