It’s probably best to have some idea what you’re going to write about – but last year I only started planning a couple of days before. I had a rough idea of what I would write in each chapter – but some of the chapter outlines were pretty sketchy.
On the day it didn’t matter – writing at speed helps you keep going.
Once or twice I ran out of ideas and borrowed from life – an overheard conversation or what was in the day’s news worked fine.
Nanowrimo grab bag
I’ve just found some writer’s software called ywriter – I only downloaded it today but it seems to have everything I need to keep track of my plot and characters, and it acts as a basic word processor.
and another word count spreadsheet – this one has a few more features than mine.
Last year I used this progress meter on my site.