To me it’s 95% or so writing good prose.
If we aren’t talking about writing the greatest novel ever, but just something serviceable, something readable that’s not a complete insult to the reader, I think there’s (mostly) something interesting about nearly every story, and even two dimensional characters aren’t necessarily a fatal flaw for a novel. Likewise, world building usually is … fine. Sure, some people are better at it than others, but usually it’ll at least be … fine.
So I don’t care too much at this point about that sort of stuff as long as it passes some basic hurdles (like, don’t add blatant contradictions and such).
But prose - there’s just no replacement for it. It’s like the ability to paint when you want to be a painter. Of course there’s also what you paint, whether there’s perhaps some sort of deeper meaning to it, and who knows what else, but if you can’t express it by painting properly in whatever style it is you choose everything else just seems meaningless to me; and for me it’s the same for writing.
And, sure, judging yourself is difficult. Maybe even impossible. I’d definitely be unsure how to rate my own prose. So I could’t tell you “I think I’m a 3/7 writer.” But I can compare it to some other authors and say “well, at least it’s cleaner than this stuff” or “definitely not nearly on the same level as what this guy writes” so there’s some goals to aspire to and some satisfaction from at least not being the worst writer ever and I guess that will have to do