Not much of a tutorial, but it is something that often needs some googling and head scratching. This is how I got my particular modem working, your mileage may vary.
Step 1) Get a modem that will work. I got a Huawei E397u LTE/UMTS/GSM modem. It's Cricket branded, but I'm on Google Fi, it will work with my data SIM.
Step 2) Plug it in and see that it doesn't work.
Step 3a) apt update
Step 3b) apt upgrade
Step 4) Install usb-modeswitcher
Step 4, optional p