I've been blogging about how to write in a more literary manner. There are multiple things to consider as one starts a new piece in order to make it deeper, more meaningful from the start. It's not just a matter of just writing or spending endless amounts of time researching. There are certain steps that will help one fully understand the story before starting.
1. First, when you have a germ of an idea, do a basic brainstorm about your story and characters. Who is your character? What era? What world? What is your basic plot idea? What is going to drive your story bus? By that, I mean will your story be driven primarily by character development (resolving your character's unhappiness/misunderstanding), plot (something's broken in the world, and your character needs to fix it), question (who dunnit?), or milieu (think Gulliver's Travels or Lord of the Rings--the most important character is the world.)
When you start one of these types of stories, it's not over until you've fulfilled the contract with your reader. Harry Potter, for example, is driven by all four. The story isn't over until Harry is happy, what's broken in the world is resolved, the mystery is solved (in Harry's case, a series of questions, one posed before the next is resolved), and the foreign world is introduced (we understand the basics of the wizarding world). I, personally, had a harder time getting into the latest Harry Potter-adjacent movies because they're more milieu-driven, more about the magic and denizens of the magic land than character development or fixing a broken world.
2. Once you have the basics of your story established, this is when you get into more detail, understanding the world of your story. This would be a good time to do your research if you're creating a piece set in a different time or with characters grappling with an event or condition you don't understand. It would also be a good time to create your map of the location. You'll also want to establish a fictional (sci fi/fantasy) magical set of rules. Your characters and plot will want to stay true these rules if you plan to keep your reader involved. They can help you develop the power sources, magical rules, creatures, etc.
3. You'll also want to understand your characters on a deeper level. At this point, you may have names, perhaps an interview with likes, dislikes, wants, needs, and a bit of a story. This is a good start, especially when it comes to wants vs needs. A plotline can be built around the conflict between what your character wants most vs what they need most. They may want to stay home and feel safe, but they really need to go on this quest, or their loved one will die.
Their protagonist's fears and desires could be the foundation for a friend or, better yet, antagonist. I always get a rough idea then decide on an enneagram (character) type, which gives me a lot more depth. These types come ready-made with a lot of characteristics. It can help you figure out your character's basic flaw and misunderstandings, which they then need to outgrow throughout their character arc.
4. Once you have world, character, and rough idea for a plot, those who feel comfortable with outlining can then outline a rough or even specific plotline. I'd recommend you refer to a three- seven- or twelve-act structure (various guidelines that walk you through the hero's journey) as a foundation. I tend to be a pantser who writes then outlines unless it's a plot-based story, in which case I use very basic outlines. One way or another, you'll want a tragectory of your story.
5. Once you understand your plot, characters, and world, it's time to simply write. I wouldn't edit, rethink, revise, rewrite in any way until I get to the end, or there's a good chance you won't finish. You'll lose steam and get frustrated. Revision comes later.
If you don't already have all this planning in, you may not be ready to write your novel/biography/etc. If that's the case, you may have some planning to do.
