I almost always have music blasting in my ears, doubly-so for writing. Otherwise my mind has a shouting match with itself.
It becomes a double-edged sword though - can't write if I'm too busy jamming, can't write if I'm not jamming lol.

I don't have anything fancy as a character playlist (which is a great idea), so it's whatever the flavour of the week/month is. 
Right now, it's Honkai: Star Rail OSTs dabbled with anime OSTs. 
My favs right now is 'Flares of the Burning Sun' (HSR) and はなになって ('Be a Flower' - from The Apothecary Diaries).