@Urfriendlydemon to be quite honest, that really depends on the style of writing you want to focus on. I've noticed that fanfiction, as a whole (as someone who writes/ reads it), is more in tune with how the main characters feel at a deeper, introspective level. For fanfic, the characters already have rich and mostly well-known traits/ history, so many readers going in already have a greater understanding of the character. You’re not just telling a story; you’re translating familiar characters through new pressure points. Voice and emotional authenticity matter more than flashy plots, at least to me.
What I recommend is to start writing small first. Short scenes. Character moments. Dialogues. Don’t try to write a 10k fic in one day. and most importantly, FIND YOUR STYLE.
Focus on one skill at a time. dialogue. pacing. internal monologue. Once you have something written out, I often sit there and read it multiple times and edit it as I go. I've noticed that this also really helps me make sure the cadence and prose of the fic stay fluid and don't suddenly change course. Hope this helps!