Not that I have any links to share but any sources that explain how to properly use some more specialized tools/equipment, when they should be used, when they shouldn't be used could fall under the category of "working safely."

As an example:

I found that the little "non contact electrical current" tester pen that I bought recently and have been trying to use to do home repairs has some caveats about when it will give a false negative. I had skimmed dozens of "how-to's" and only a few of them mentioned that using this tool to check electrical outlets won't work if the outlets aren't properly grounded (I live in a shitty shitty house, a chunk of the problems wind up being things not done properly). And I think the same thing might apply to checking Romex cables but I haven't spent the time to try to find out for sure.