Generally speaking, writers tend to fall into one of two camps: plotters or pantsers.
Plotters tend to have a very organised approach to their writing, and spend a lot of time writing up outlines of how the story is going to go. Outlines can vary from being a one or two page document with the main storyline written in, to multi-page manuals on how the story will be written, chapter by chapter, from beginning to end.
Pantsers are different. They literally write by the seat of their pants. They have a nugget of an idea, and just sit down and start writing from there. The plot forms as they write, they invent it as they go.
There are pluses and minuses to both. Those who plot and outline generally have less rewriting to do. Pantsers may find that their story takes a turn half way through that means entire chapters have to be consigned to the waste-paper basket. But they can also allow their characters to set the pace, and make decisions on plot as they evolve. Plotters work can be more rigid.
So which is better? Honestly, whatever works for you. Personally, I tend to write the first half of a novel without a roadmap. Half way through, my momentum starts to give out and I need some structure. I sit down with a paper and pen and sketch out a plan for the remainder of the book and continue from there.
When you research the whole novel-writing process, you'll find a lot of 'rules'. The only ones I found that I think should be set in stone are 'make time for your writing', 'write regularly', and 'edit, edit, edit'. Everything else you have to try out and see whether or not it works for you.
What about you guys? Are you plotters or pantsers?