“Writing a novel is like driving a car at night. You can see only as far as your headlights, but you can make the whole trip that way." E.L. Doctorow
Whether or not to outline a novel before writing it, or how much to outline before beginning, depends on the individual needs of the writer, and the story. In fiction, outlining is more common in plot-driven genres because of the complexities of the twists and turns required by the story. Some writers need to outline no matter what the genre, and some refuse to outline, even in plot-driven stories, preferring instead to let the subconscious plot the story as they write.
If you chose not to outline, I recommend meditating on three or more key scenes in the story early in the process of writing. The key scenes will usually contain the delivery of major turns in the plot. The first key scene will be the one that launches the dramatic action, the inciting incident. The second key scene will be the climax of the first set of dramatic implications of that inciting incident. The third key scene will be near the end, and this can be as vague as a feeling for where you want the characters to end. This approach gives writers a target (the next key scene) and a trajectory, while allowing the subconscious to move the plot. When you reach the second key scene, think about the next key scene that involves a major change in the characters/plot, then write toward that scene.