I'm more interested in what stars/constellations <b>you</b> use to determine it, rather than the theory
I've always known the theory, but never bothered to actually find a constellation and map the magnitudes of the stars, and find which ones I can see.
It will be useful as a statistics and log type of thing, to determine good nights from bad, and whether there's increasing light pollution around you etc.
and also to compare the VLM's when you go from your home to a dark sky site.