What CRISP is supposed to mean: Correct Readable Idiomatic Simple Performant Notice that all this is just well-wishing and suitably vague, so that you feel the need to buy a book & hire a consultant to explain it to you. The trick is there's nothing to explain.
Correct: the primary objective. Code that does what it's supposed to, bug free.
Readable: strive to write code that will be understandable by others (and your future self). Review what you wrote and be your own critic when it comes to clarity.
Idiomatic: Write code the way people in your community expect to read. Don't surprise them with your own quirky and clever conventions, when there are well established and perfectly acceptable ones already.
Simple: Your code should do what it says it does directly, with no funky side-effects. Repetition is not always a sin, don't DRY things up just for the sake of it. Don't do too many things. Be parsimonious.
Performant: be aware of RAM (a bit of a letdown).
The last point was disappointing, as I was expecting something about coding to data structures when it matters. Instead the author went on about being aware of memory.