Why haven't you started?

There are so many reasons to procrastinate.

You have to do more research. You have to learn more about writing. You have to get your life in order so that you have enough regular time to write.

There are so many reasons to procrastinate and there will always be more.

There is one very good reason to start writing now, however: Your writing won't get done until you start.

Keep researching and learning and organizing while you write if you have to, but start putting those words down on paper. That's the only way you're going to get any real writing done.