All the things
It's surprising the number of things that need to be done after you're done writing a book to give it a good shot in the market. There's a lot of supplementary writing to do, and, nowadays, a whole lot of marketing effort that authors need to be put in too with things like making a website, newsletter, social media post and things like that. And I've done all of that and continue to do so for my novel "Under THe Full and Crescent Moon"