Jane Friedman has a great post on how to write a book in three drafts. There’s the messy draft, which is a first draft and often unorganized. Then there’s the method draft, which outlines the messy draft and starts the rewriting process. And last is the polished draft, where you start asking people for constructive feedback from beta readers.
After getting feedback, you can go back and take a look at your paragraphs. Joseph Blake Parker offers six tips on how to write strong paragraphs. Basically, you want to know what kind of paragraph you’re using (descriptive, action, dialogue, etc.), determine paragraph lengths depending on whether you want to slow a scene down or have an action-packed scene, and use important words only one time per paragraph.
Next you can use tools, such as Grammarly or the Hemingway app, to help clean up your manuscript. There’s also After the Deadline, an open-source plugin/extension/add-on/etc. that uses AI and natural language processing to find errors and offer suggestions.
After all that, you can choose to either self publish your book or to try and go the traditional route. If you want to go the traditional route, Writer’s Digest has a guide to literary agents, where you can learn more about agents, and get tips on how to query and submit.