Answer by David Throop:
Just Get Started
The first question to ask, I believe, isn't how does one being to write but how you're going to outline your thoughts. The mistake it sounds that you're making is that you get caught up in what I call the "dream" phase, the imagination, the plot, the characters and spend your time hotting those down.
The Muse and Passion Myth
Passion is a great thing to have in this phase.
But passion alone won't get your writing done. I wrote about this on my blog about getting, and staying, motivated here
You also need to be disciplined
What you need to do is just get started.
Let me say that again – Just Get Started.
Use your notes and ideas from a day or so before and just start writing about them. If you spend 20 minutes to start your writing, the imagery, the motivation will begin to rekindle itself.
Once you remind yourself of how the imagination – "dream" – phase felt like, you'll be more motivated to progress your story, book and ideas forward.
I recommend writing in short bursts of time with intermittent breaks. This is known as the Pomodoro Technique and is something applied to productivity. It states that productivity increases are due to short, intense bursts with intervals of time off. They recommend setting a timer for 25 minutes, which you would use to write. At the end of the timer, you then take a 5 minute break – no exceptions!!!
In short, you need to sit down, get started writing and take a short break.
Try it for a day or two then add a second session to your writing. Once you feel like you've stretched out your writing skills (think of it as a muscle), then add one additional session a week.