Many writers have a vague idea about wanting to write, but don't know how to get started. Or they get started, and wonder, what now? In the beginning, it's best to keep it simple. You'll be overwhelmed quickly if you sit down to write the-next-big-hit-sure-to-be-a-major-motion-picture-in-no-time. To borrow Anne Lamot's analogy ( Bird by Bird: ), allow your writing to evolve in its own time: brick by brick. Create a shelter for yourself and your characters to feel safe in. Step One: Write Better to get your project out of your head, no matter how unprepared and raw it seems. You've been thinking about it for a week, a few months, even YEARS. Lay your groundwork. It's like building a house, you have to start with a frame. Don't wait for all your materials to be there before you start, or your "land" may be swept right up from under you. You have to begin with what you have now. Just start writing, there will be time to set aside the any scrap ...
Edit your excuses! Stay happy, healthy, and creative.