The folks at 43 Folders had a clever idea-Google "rules of thumb" and see what comes up.
They found rules of thumb for flirting, evaluating a pet store, building a church (balconies? not hot) and selling remote controls.
We all have personal rules of thumb, of course. For instance:
-If Ice Cube is in it, I won't be renting it
-Brown clothes in my wardrobe are too much hassle
-Buy the canned tomatoes; the ones in the produce section will just break your heart.
These are fine but they aren't a system, they're just ad hoc ideas. But I know within me, there are rules, rules I follow, some I've developed and some I've borrowed and many of them make systems.
Between the time I started typing this post and now, I went back to the posting at 43 folders. There are many comments from readers including this helpful hint:
If a helicopter is bigger than your thumb held at arm's length, you can bring it down with ground fire.
For any of you who are too distracted by the concept of "the rule of thumb" because you are busy thinking about how the phrase "rule of thumb" refers to an old law requiring men to restrict themselves to beating women with a rod no greater in diameter to their own thumbs, this site claims that story is bogus. The site goes on to say that, per the O.E.D., "rule of thumb" has been used at least 300 years to refer to any method of measurement or technique of estimation derived from experience rather than science.