Ralph Landry1, greetings: I discovered electricity and learned about circuits when I was about 4 years old. I stuck my fingers into a wall outlet and have never done it since. This was one of the few times that I was a fast learner.
Seriously, a good tool to have is a high quality VOM. Serious testing cannot be done without one as you well know. But if you don't have one, the 'in the Amazon' techniques that you describe are better than nothing.