I think the idea of "a quick art" is conceptually almost perfect but I'm not sure about the latin declinations/conjugations and it doesn't sound pleasing to me somehow, as in "That's a neat ars brevis you showed me, thanks!"

Thinking about it more maybe "lifehack" is so close as to be as good as we're going to find? The quibbles I have with it still are:

• Whereas "a technique" is too generic, "a lifehack" it feels too narrow -- like I wouldn't expect someone to share a solution to a solution to a common failure mode in physics classes if asked for a "lifehack". I think the perfect word would be a parent category for lifehacks :-)

• Like a trick or a cheatcode, a "hack" also has negative connotations with many people, either as a malicious computer break-in or as a sloppy solution one step up from a kludge. It would be nice to have a word that someone unfamiliar with would be complimented to hear applied to a technique that they have shared.