For common mistakes, I have created a basic guide on mistakes to avoid, which you can find here—though it is geared more towards plants. There’s also a few useful links to tutorials in there that I found useful, though some are more long than others.
(There is a copy that I put on the forum Tutorials section, but that one is out of date)
I got hooked onto iNat after watching this Youtube video done by PBS Studios. I find that a useful introduction to what iNat is and why it’s important, while also highlighting the enjoyment you can get out of it.
In terms of getting other people to use iNat, especially if it’s a larger group of people, I would suggest not to make it mandatory. Forcing people to use this platform is the equivalent of dragging a sulking child to the playground. Find those who are really interested in what iNaturalist has to offer, and once they get onboard they can spread the word to other colleagues and pull them in as well.