I got made fun of as a child by a parent for doing art and just... never did any ever afterwards. I primarily hang around artists tho and would like to relate to them more, but none of them do creative writing. I've read numerous grammar books, so that won't be a problem, but none really go in to how to construct a sentence, paragraph, page, chapter, plot, etc. I'll happily take any advice on the subject, really anything you can think for someone with actually zero experience.
Good advice I've gotten so far is to just write basically whatever. Also, people who are visual artists and creative writers, which was "easier" for you to become fluent?
I'm not an artist or imo a very creative person but i did try my hand at a bit of creative writing when i was younger. What i concluded is that you can learn all the theory there is to learn and still not be a good writer. At the end of the day the best recommendation i can make is to just read and read a lot. After a few hundred books you will get an instinctive feel for what is good writing and what isn't, what feels natural and what doesn't.
I think a lot of writers start by emulating the styles of other more experienced writers and over time they develop their own style. Of course for that it is essential that you get a lot of practice, so you should just start writing even if it's bad at first and you will naturally improve time. Really this goes for pretty much any creative activity. I find it's the same for playing an instrument, and i assume also for visual arts but that is out of my range of experiences.