hi mousie!
i pretty much always make moodboards for my fics these days. i never used to, but since i got back into writing last year i've found it really helpful. it's nice to have them as like a 'cover' for the fic on a promo post. but i also make them and insert them at the top of the doc while i'm writing. i find them a good way to remind of the vibe/mood of the fic. and sometimes looking for images for it and making them directly inspires certain scenes/settings in the fic. when i was making my moobboard for in the mist i found this image of statues of hands clustered together and it inspired 'the Agnoy' location in the fic. or for your touch embroiders me i found some pictures that were essentially ballet dancer thirst traps, and it inspired the section of the fic where mnh starts sending jsvng thirst traps everyday.

playlists i don't do so much. i do listen to music or watch shows while i write, but i think i find moodboards more helpful because it helps prompt visual ideas for me which i struggle with because of aphantasia. i did make a playlist for your touch embroiders me which i looped on repeat for months, and ended up giving me the title of the fic. other than that there may be a song i listen to a lot when i write a fic, but i wouldn't say its common.