Hello! I am published on Amazon, and although I'm definitely not a professional, I'll share my thoughts with you. (Please take them with a grain of salt with no direct commentary on your skill as a writer.)
- Cover Art - When you get into the realm of paid book self-publishing, unless your platform is making your cover for you - your cover needs to be as professional as possible. While there are readers who will happily read anything on a platform, poorer quality covers do not sell well. It's not uncommon for writers to re-cover their books multiple times over the life of the book.
- Get an editor. I don't often recommend editors because there's a lot one can do on their own. But I would highly recommend working with someone who understands the differences between web novels, traditional novels, and enovels.
- Rewrite. Rewrite. Rewrite. You definitely do not want to rush to get something published and regret it. You can always go back and fix it later, but the readers have seen it. Don't rush to publish. Work it until it's the best you can do before making the plunge. But don't be afraid to make the plunge.