I think every writer will agree that it's one of the most frequently asked questions. I answered it several times in this blog, it seems easy to do in this impersonal way, but when it comes to answering face to face I go blank. Having answered it innumerable times over the years I feel deflated, like a balloon letting air out bit by bit until it's empty. So, in the words of Agatha Christie I result to a short: From my head. Then I feign sudden thirst and rush to the drinks table.
I am tempted to print out Agatha's answer, carry it in my wallet and hand out to the curious:
If one idea in particular seems attractive, and you feel you could do something with it, then you toss it around, play trick with it, work it up, tone it down, and gradually get it into shape. Then, of course, you have to start writing it. That’s not nearly such fun – it becomes hard work. Alternatively, you can tuck it away, in storage, for perhaps using in a year or two years time.