Writing a novel is a marathon, not a sprint. I was once advised by author, Allison Symes, "You better like your first book because you'll be thinking about it for the rest of your life!" She's right - so make sure you get it right.
Planning is fantastic, in fact most authors would say it's essential but don’t let meticulous planning keep you from actually writing your novel. The first draft of your first chapter may be terrible, and it may end up being totally rewritten once you’re done, but it’s important to dive in before you’re paralyzed by second guessing. It’s okay if this draft (sometimes called a rough draft) is overly long and full of typos or plot holes. Believe me when I say you’ll have time to revise. In fact, Terry Pratchett used to say that the first draft is just telling yourself the story.
When you have finished your first draft, spend some time away from your novel. This allows you to approach it with fresh eyes when you read it back some weeks or even months later. As you review your first draft, pay attention to the clarity of your story, character development, depth to your world-building and the pacing of the action.
At this point you will consider what is needed in your second draft and, depending on your assessment of your first draft, you may opt for surgical edits to specific scenes or you may diagnose that your novel needs drastic changes. If the storytelling is seriously deficient, you may choose to embark on what’s known as a “page one rewrite,” where you literally start from a blank page and reconstruct the novel.
Most writers will commemorate the completion of a second draft by sending their novel to trusted readers, known as beta readers, for their input. These readers could be friends, fellow novelists, or a professional editor. When fielding outside notes, pay careful heed to similar notes that come from different sources. If two or more people point out the same issue, it’s probably worth careful consideration. Also note the difference between diagnosing a problem and pitching a solution. Some readers might identify a flaw in a story line or character arc, but then they pitch a fix that doesn’t resonate with you. Take their advice to whatever degree helps you execute your vision for the story. Ultimately it’s your novel.
There is no fixed number of drafts that will ensure a novel’s success. Some novels can reach the publication stage with only three drafts plus a light round of editing known as a “polish.” Others might go through a half-dozen drafts or more. Some drafts have more to do with cosmetic changes, like unifying your language or cutting down on word count. Others involve wholesale changes to the story itself. No two novels are alike, so prepare to encounter both challenges and triumphs that are unique to the specific novel you are working on. However, you should make sure that the book is as good as you can make it before you submit it to an agent or publisher or self-publish your novel.