I wanted to write a novel, but I thought: if you are going to write a novel, you have to write a novel about characters, and characters need desires, to motivate them. Characters can't just do whatever you want because you say they're going to do it. A good novel has a plot.
Ok, a plot. So, we need characters with desires and a plot, but what's the point of this plot? The plot is the long-term result of the interactions between the characters' desires and the actual conditions of their lives, compounded over and over and over. The timing, the spacing, the rhythm of desire action motivation interaction speech silence sleep etc. All of this constitutes a plot. And what is a plot for, why tell a story in the first place?
I guess you tell a story because you want to watch people doing something. What do you want to see? Maybe you want to see the struggles of a starving young writer who is convinced of his own greatness and has no source of income, and maybe you want to watch this fellow recriminate and curse himself for his stupidity and weakness and lack of success. Maybe you want to trace the progress of a little Scandinavian orphan girl as she wanders south into central Europe and attempts to make a living in 16th century Germany amidst the chaos and hostility of the times. Who knows what you want. But you want to see something, and that's what you've got to show.
Ok. So let's figure this out. I'm going to show something in this novel, and from the standpoint of the novel's construction, the thing that I want to show comes somehow first. Otherwise each decision will be almost unbearably difficult. How are you supposed to make decisions for a couple dozen characters, when you don't even know how to make decisions for yourself? I guess the answer is that you don't make decisions for them, you place them in a story which dictates the sorts of things that your characters will do, and then that dictates the characters and retroactively creates the personalities.
Remember that in a novel all you get is the barest sheen of description. The mind of the reader fleshes it out and makes it real. You are merely a guide for the reader's imagination. You do not need to create the world of the novel. If your novel is ever to go anywhere or do anything, you cannot effectively create the world in which it takes place, because the abundance of description necessary to pull off such a task would prevent you from ever getting around to saying what happened.
So what do you do? You sketch out a kind of story with kinds of characters. You give clues to the oddities and personalities and the character of the places and events, and these clues act as cues from which the rest of it is constructed.