You need this userscript to make the art visible: Display cover arts in MusicBrainz pages: “mb. FUNKEY ILLUSTRATED RECORDS” (If you have never used scripts, here is a How To Install from the RAW button on here )
And a quick search you’ll find plenty of discussions pop up now and then on the artwork.
Various tickets around are expanding on the types we have - matrix, top and bottom appeared in the last few months.
I think you’ll find there is plenty of focus on art - just watch how fast the new cover ticker moves on the front page. We all have our own methods and tips often get shared.
Your best option is just dive in and start making some threads. Share your methods as people will be interested.