Sometimes I can look back and see where the idea came from, or where two odd thoughts collided and created something new.
For me it usually starts with a character, or a disembodied line of dialogue pops into my head which prompts me to ask "Who said that?"
One year, for the NANO novel in a month competition I deliberately refused to think about it until the last minute. At the stroke of midnight on October 31st all I had was a post it note with three words. Speed, motorcycles, candyfloss. I had a vague idea about a storyline with a female wall of death rider.
In the end I dropped the candyfloss and wrote 50,000 words about a female motorbike restorer and a record attempt.
By quarter past midnight Sam(antha) was real to me as any other of my characters, although it took a while to truly discover what made her tick. Now that first draft has taken a background place to more pressing matters, but she's never truly gone away. Persistence is the mark of a good character. If they won't leave you alone, you have to write about them.
Gyppo