It's the start of a new academic year and I have a new group of students attending my IoT Club.
To help them get their very first node to work I recently wrote this tutorial guide.
I was amazed how many things can be overlooked or wired-up incorrectly on a very simple circuit.
As with most of my projects, a Wemos D1 Mini is used to provide the control/sensing interface (rather than risking the GPIO pins on a Raspberry Pi) so the guide also covers getting the MQTT settings to match those on the RPi.