Well, first I think that's a very personal thing and that every author will have their own take on this. There's no right or wrong way. As W. Somerset Maugham said: 'There are three rules for writing a novel. Unfortunately, no-one knows what they are.'
Basically, I prefer the Stephen King approach as set out in his 'On Writing'. You know, the book he wrote after he was hit by a truck when he was out walking to clear his mind after a writing session. The truck that nearly killed him. You get the idea that he felt he had to put it all in that book, just in case.
I take his approach to be something along the lines of: If you're not surprising yourself when you're writing your book, how can you hope to surprise your readers when they're reading it? So, I try to be excited at what's coming out as I write and let the novel plan itself. With this approach, you don't start with a detailed, worked-out plot or anything more than a part-glimpsed plan, you really do let the characters tell you what should happen next.
Generally, I don't believe in heroes. I wouldn't want to trust one. I get more from ordinary, flawed, people in situations that take them out of their normal lives. Then things get interesting as you see how they struggle with what seems for them the impossible. And I want to resolve things in the end in their favour. My way, if you like, of righting some of the wrongs, albeit in a small way.
There are two of Stephen King's aphorisms that I take seriously. The first: 'The road to hell is paved with adverbs.' So, where at all possible I don't use them. The second: 'Any word you have to hunt for in a thesaurus is the wrong word. There are no exceptions to this rule.' I never use a dictionary or a thesaurus.
Finally, I'd emphasise the importance of the 'polishing' stage in the writing process. Once the words have formed themselves out of the characters' wishes, once the story has been told, the real work begins. Writing and rewriting, working and reworking the text to give it as much shine and polish as you can muster. And there's then always the hope in discovering another of the goals suggested by Stephen King – that seldom achieved 'gem' where you contribute a striking and novel turn of language that lights up the whole show.