I'm writing (planning to write) a fantasy novel. I'm done with the worldbuilding, rules of magic, main characters (even though I think I will add some more in the future) and their initial plots and interactions. The problem is that I don't have a clear idea of what's gonna happen in the middle/end of the story. I only have vague ideas.
Should I first complete the storyline (at least the main events) and then start writing or should I start to write and see how my characters behave as I write?
Lots of writers start writing with no idea where it will go, much less how it will end. Dean Wesley Smith has a book about that, called Writing Into the Dark.
On the other hand, I once heard Richard North Patterson claim that "Any mystery writer who starts without knowing the end is committing authorial malpractice." (The next time I read one of his books, I knew the ending about 25% of the way in. And the one after that, I figured out on page 8. So go figure.)
If you have some way of progressively moving in the direction of a climax, that will help. You don't even have to know the climax. You just have to know that you are moving toward one.
A pretty good way to do that: Start with a character with a problem. Then write try/fail cycles. The character tries the smartest thing they can think of. But it fails. Not only that, it leaves things worse than they were before. So they try the next thing, which is more difficult in some way.
This progresses (more or less) in the direction of a climax because eventually the character runs out of easy ideas, and has to try harder ones, or ones they are more and more reluctant to try.
If you keep that up, you get to a point where the only way forward is to do something the character has sworn all along that they would never do. And you have discovered a climax.
My advice: Whichever way gets you writing is the right way (for now).
Even if you end up throwing stuff out, everything you write is practice. It's learning. That's worth a lot.
A Plotter works out the whole book, chapter by chapter, point by point, then writes to the outline. It takes a long time up front, but then writing can progress quite quickly.
A Pantster, on the other hand, writes by the seat of his or her pants, sitting down, clearing his mind, and then writing what comes. JRR Tolkein could be described a pantster I believe. For a pantster, the first draft is often quite scrappy and inconsistent.
In my WIP, one of my characters has Alzheimer's in about half the chapters and a daughter in the other half. My hero's hair changes colour. I have a half dozen chapters that need refactoring to make them consistent. The first draft functions like an outline.
There's an intermediate stage called a Planster: a person who has a general idea of the main plot points, but who discovers the details on the way.
There are many different ways to produce a book, and you'll discover your own style as you go. Don't be told that there is only one way, there are lots as you'll discover.
Not all writers know exactly where they're going when they start writing. Sometimes, they don't even know what the first turning point will be until they pick up the pen, or get on the computer, and start typing/writing. If you're not quite sure about the story-line yet, then maybe starting the first chapter is exactly what you need to do to get the creative juices flowing. In quite a few of the stories I've written, and completed, I had no idea how it was going to end until I'd already written the climax.
For me, it doesn't matter whether I know where a story is going or not, because I can only type so fast. I love to flesh out characters and plot out outlines while I'm preparing to write, but once I start writing, all bets are off. The finished product rarely looks like I thought it would as I started typing the opening scene. That used to bother me, but over the years it has become more of a reassurance. Each night, as I sit down to write something new, I assure myself that I don't have to get anything perfect tonight. Between now and final edits, everything is likely to change.
Writing is organic. While we write, we grow. The story grows. Our talent grows. Everything changes between conception and birth. You are not the author you are going to be by the time you finish this book and like that future you, the book will be different from what you expect. Don't worry about how the story ends. Let the future you figure it out.
The most important thing (the only important thing?) is the end result--and that someone reads it.
Of course, the process to get there is important, because, duh, it's how we get there! But any way you do it, if it turns out good, it's a good process.
It's your process!
Imitation is important - feel free to pick and choose from other people's processes - but in the end you're going to have to invent your own process that works for you. Don't be surprised if it evolves from one book to the next.
Your personality might help deciding which way to go.
As has been said before, there are two main ways to write a book. Outlining and Pantsing. And then there are a myriad of combinations and variants of those two...
What I've found (I've used both approaches) is that pantsing makes for a very messy first draft. You have to love picking your story apart, rewriting, moving stuff around, putting stuff together, experiment, throwing stuff away! And so on.
Pantsing can be a good thing though if your creativity takes time to get going and you feel that you don't have the ability to just be creative within the small confines of a single scene. If you have to have the whole organic flow from beginning to end, pantsing might be your way to write a book.
Outlining on the other hand (usually) limits the chaos of the first draft, although you're still going to have to write several drafts. However, outlining requires more of an on/off-switchable creativity that you can use to go in and just create that scene, then move on to the next scene that may be years later, some place else or with a totally different group of people. (Of course, with an outline you can plan your scenes in one order - jumping between plots, locations etc as you see fit - and then write them in an other order as to limit the amount of disconnect).
Personally I'm clinically impulsive, so pantsing turned into a pretty varied assortment of "stuff" (A.k.a. total mess!) Outlining fits me better since I can just go wild with that one scene and it's "contained" within a reasonable story structure.
The kind of book you're writing can suggest one way or another.
If your book has a complex plot with many twists (e.g. books in the crime/thriller genre), outlining the story first might be better to avoid having to throw so much away due to logic holes.
Other types of books might work better with pantsing.
You don't have to know how it ends, but you do have to know how it begins. It begins with some pain, some longing, some need, some disturbance in the equanimity of life that forces some deep deviation from the ordinary course of affairs.
You don't have to know how the deviation will end, or even what course it will take, but you have to know what it is and why it is. You cannot meander along waiting to discover it or waiting for it to happen of its own accord. Or rather, you can, but nothing worth keeping gets written till you find it.
I find it odd that some writers scope out their story, beginning to end, before writing it. Where's the fun in that?
I never know how my stories will end. I learn about the end as the characters do. The ending flows naturally from the characters' actions through the story and their, well, their characters. I can't prescribe an ending on the story, and on these characters. They change as they're written, and in revision, so it's futile to specify ahead of time what they're going to do and how the story will end.
