Learning to Learn

Give learning Japanese a try. It's a meta-learning adventure! There are 3 distinct classes of characters (two syllabaries that each have a perfect matching pair with the other, 46 each plus some compounds) and the third are (mostly) chinese Kanji characters. Fun stuff!

I wonder if there is a similar "Pareto priciple"-esque approach that one could use to learn Japanese.

There are the "radicals" which can help you to interpret a new kanji, since they're the kanji building blocks.

Kinda!

The frequency of words in every human language follows the Zipf distribution, which is a power law, like the pareto distribution.

Some learners create what are called frequency lists, which are lists of the most common words, and learn those words first. In general, you get (disproportionately) more bang for your buck from learning the most common words than the rarer words when it comes to understanding.

However, due to the very long tail of word frequency distributions, you eventually need to just start learning words as they come and stop trying to over-optimize with a frequency list.

I highly recommend this site for that. https://kanji.koohii.com/ which goes along with the book "Remembering the Kanji" by James Heisig (strictly speaking, you don't need the book, but I think it will help understand the idea behind the process). But the stories (mnemonics) on the website are better than the ones in the book, but also let you put in your own stories. You can also vote and choose existing stories, so there are crowd sourced mnemonics that other people have said work for them. One interesting side effect of that is a lot of people decided to use Spider Man whenever there is a "thread" radical, for more memorable stories. I did it around 15 years ago and learned how to write all the 2000+ commonly used kanji in a few months (9 months for me; 2-3 months for a more diligent person). It uses a spaced repetition system (Lietner box method).