And when you write your first book, avoid Mistake 101, the curse of the aspiring author. What is it? Writing three or four chapters, and then going back to them and rewriting them over and over again until they are "perfect". Forget perfection - it's not going to happen. Completion is key, and perfection is the enemy of completion. The solution: write the first draft. All the way through. To the end. And ONLY THEN go back and start revising. That way you have a first draft of your book, which is better than having three awesome chapters and no energy/money/time to go any further.
Also, use Scrivener. It's a great piece of software that I used for my book, and it's cheap ($40 or thereabouts).