What is it about writing your first book that is so hard? If you did have a lot of classroom education, it may not be so difficult. What if you didn't? Yeah, well. About that, little things make a big thing. No matter who you are, books don't write themselves. Giving yourself permission to write is harder than it sounds, because you've got to be in touch with parts of yourself that are not always good, kind, decent, or nice. Good Guys and Bad Guys alike all have origins, motivations, and behaviors that are sometimes a little ticklish for many of us to portray.
It's never quite so simple when you need to write mushy stuff, to demonstrate a character's empathy. Nor is it easy to portray a villain with all the depth and credibility they deserve. That's why some parts of the novel writing process are the way they are. Even a good How-To book requires some structure and planning. It may not seem like it, but these two things have one factor in common: planning and forethought.
I've known many people who don't like to scribble out anything like an outline. They hate it, don't think they need it. Hey, come on--you know the story, right? No, you don't. Thinking about it and putting words on a page are not the same thing. Most outlines I crunch out today are bullet points, just enough to keep me on track. Why? Novels are broken down in to chapters, even a How To has chapters, sections, and sub-sections. Knowing what these are before you ever get to them does matter because that outline makes you think, and it keeps you honest.
I have wanted to write some things as a collection of short stories. Later on, I changed my mind when it became clear enough that there was a lot more to work with than I thought there could be. I would not have "seen" that without an outline to work from. That's actually how I developed my first anthology. Let's stick to novels for now, novellas and anthologies are separate subjects.
Outlines and the chapters that spawn from them really do serve one more less-than-obvious purpose. the help you with Character Development. Academics (e.g., historians) have a built-in advantage when they cite and footnote what somebody said or did, because they are presenting that material in a structured way that helps you understand it. Fiction writers don't work with that kind of net, they have to portray what somebody is or does in a different way. Seeing all that play out in sequential chapters gives you a chance to build a map of sorts. That map explains who your characters are, what they do, and why they matter in the larger scheme of things.
There is no one right way to do all this. Outlines force you to think before you act. Chapters force you to develop your characters more consistently. Stream-of-consciousness is good for many things, making it up as you go along can be done--but--it's not recommended for that first novel. Nor is it a good idea to try it when you're not fully up to speed on a subject you intend to write about in detail. Self-published writers take a lot of flak because--sometimes--they don't pay attention to quality control, story development, or the nuts-and-bolts of characters they create.
That's why process matters.