Perseverance. Most people think it’s only about talent, but it’s not. Writing is a craft that you’re continually refining. Not many authors get their first book published (or their second or third for that matter) so you have to persevere, despite multiple rejections from agents and publishers. That’s the toughest part.
You also need self-discipline, and loads of it. You have to be able to sit down at your computer and make time to write. In the early days when your book is a ‘sideline’, you have to put other things (like your social life and TV!) on the back burner. Focus.
That depends on what the book is and whether I’m working on it full time or not. To date, I’ve worked in the corporate field while writing books, and it’s generally taken me about 9-18 months to write a first draft, depending on whether I’ve been working part time or full time.
Lots of my ideas come from dreams, often scary ones! I tend to sleep quite lightly and often wake up with a good idea for a book. Unfortunately, if I don’t write it down there and then I find by the time I wake up properly, I’ve forgotten the dream.
I also tend to get ideas when I’m relaxing and ‘away from it all’, especially near the ocean.