Easing into ConTeXt (ConTeXt 101)

Starting point: You have installed ConTeXt, don't understand what to do with it. Maybe you've seen books made with ConTeXt or you've heard that it is better for big documents than e.g. Word. Or once upon a time you tried using LaTeX because you really need to type math, but it just didn't work out. Or you wanted to do things outside of the existing LaTeX classes/templates and can't be bothered to go that far into the inner works of the system, when things are supposed to be easier in ConTeXt.

Whatever the reasons, you want to learn ConTeXt, but in an easy way. If it turns out that your local ConTeXt installation isn't working after all, you can do most things mentioned in [ConTeXt online], although that one is still running an old version of ConTeXt (MkII/pdftex or XeTeX). If your own newish installation - which should be MkIV running LuaTeX - works, please use it so you get to profit from all the tips and tricks!