The most essential element for a person who has just started writing his or her first novel is passion and commitment. This is a marathon not a sprint.
There are a number of ways to look at this question — let’s begin with subject matter. Do you know what you want to write about. Try — it’s hard! — to write what your book is about in one or two sentences making sure you compress the plot and emphasize the juice of the book. Here is an example from my novel that I crowd-sourced for the cover letter that went out with the galleys: “The first biographical novel about Josephine Marcus, Wyatt Earp’s wife, the gutsy Jewish beauty who captured the lawman’s heart in 1881, the year he fought the legendary Gunfight at the OK Corral.”
Who are your characters? Pause and write down as much as you know about the two to five main players. What do they look like, what is their personal history — what is their sign even. What do they like to eat? What aggravates them? Do they suffer from headaches? Prefer dogs or cats? Oldest child or middle? Ethnicity?
Begin the first chapter — does it have a unique voice? Will you tell it in first person or third, will your third person be omniscient or limited. Meanwhile, you can begin to outline. Not every novelist outlines their books. Some know the shape or the starting point. A picaresque, like my first novel or Don Quijote or Moll Flanders or The Diary of a Chambermaid, is a journey that meanders from adventure to adventure. I like to know at least three chapters ahead.
In the case of The Last Woman Standing, I wrote the first three chapters, knew where I wanted the entire book to land, and then talked out the progress of the chapters with a trusted editor. There were points where the map changed as I wrote but that was alright because I knew my destination: that my characters Josie Marcus and Wyatt Earp would reunite on her stoop in San Francisco (even though originally I had her sitting with her brother and she ended up there with her sister).
While I had an outline, one of the most ecstatic thing that happens to a writer who commits to a novel is the moments when the characters begin to act of their own free will. You have created them, you have put them in a situation — and then they begin to tell you how they behave in a way that’s true to their natures not yours. I call this hydroplaning because suddenly I feel that I am free from the road and flying — my fingers are still on my keyboard but they are channeling the fiction rather than forcing it. When you experience that as a novelist you’ll know you have arrived.