As NaNoWriMo approaches, there's one question that is important above all:
Are you a planner, or a pantser? Or maybe a little of both (a plantser)?
Right now you have nearly a month before NaNoWriMo starts, so now is a good time to decide which style you prefer. If you're a planner, you'll probably want to get start on planning pretty soon so that you're ready to write on November 1st.
Planner: The kind of writer who goes in with everything already figured out. Worldbuilding, character development, story plot, everything is already done, sometimes in great detail. If you're the kind of person who plans out each chapter and what's going to happen in it before you ever start writing, you are a hardcore planner.
Pantser: This is a NaNoWriMo term for someone who just totally wings it. You might go into the month of November with a story idea, but it's admittedly fairly general and you have no idea what's going to happen next 99.99% of the time. Maybe you know how you want to end it, maybe you don't, but chances are you don't know yet how you'll get there. You let the characters and the story tell you where they're going as you write.
Plantser: No, this is not a plant. This is a perfect (in my opinion) mix of the two options above. You plan, but not so much that you lose the creativity that tends to show up out of the blue while you write. Maybe you have a loose sketch of the events that take place in the novel, but you haven't planned each chapter down to every scene break. You're not so wedded to your idea that you can't drop it all and follow a side character across Europe for no reason at all except that she stood up and told you that this was actually her story, thank you very much.
As you might have guessed, I usually fall in the general realm of plantser. I tried pantsing once, and it didn't go terribly well: I petered out way earlier than usual. I also tried planning everything up the wazoo once, and I didn't get very far out of the gates before all the wind went out of me. So plantser is definitely where I live.
What about you? Are you hard at work at planning for NaNoWriMo, or are you just planning to start typing at midnight on November 1st and see what happens?