Here is a quick post about what you need to focus on as a writer. There are plenty of important skills to master good fiction writing. Crafting complex interesting plot, creating compelling characters, dazzling prose, strong important themes, having a distinct point of view or voice, all of these are important.
But.
I think we can all recall novels and short stories where one of these elements was less than stellar. Books that are massively successful despite some poorly drawn characters, tired cliched plots, or that they brought nothing new to light. (Mind you I don’t think aside from self-published material – and only some of them not all by any measure – do you find all these faults in one work. But many works survived with one or two of them.)
There is a skill that every published author has mastered no matter the material.
They finished.
The story didn;t end up in a forgotten drawer, on in an uncompleted file on their hard drive. The author stuck with it, did not give up and chase a new shiny idea, but did the work and wrote to the end.
This is the most important skill, learning to finish. Because if you can’t, none of the other things will matter.