But one factor I know plays a great part is 'shape' - by which I mean the architectural shape of a story, the shape upon which everything else hangs.
It can take me a while to find the right shape of a story in my head; but once I can see that shape, there is often a flow to my work that I find very reassuring.
Recently I finished the first rough draft of my Barry Reckord Bursary play Treading Air. It was a challenging piece to write, for all sorts of reasons, and to finish it felt like something of a relief. I could still feel, however, the struggle in the words I'd written. I knew it wasn't right, and that it still had a long way to go. And this was largely due to the fact that, try as I might, I hadn't been able to build a clear, firm shape.
I'd found threads, I'd formed a skeleton, I'd fleshed it out. But it was ungainly. There were moments, yes. There were peaks, troughs and all the things you need in a narrative. There was something there. But the shape was a misshape.
Of course this is all part of the process. It's why you have drafts - so the work can develop and evolve. And it's true that sometimes you need to be drowning in the depths in order to look up and see that perfect fan of illumination....
So now I've begun the second draft of Treading Air and, just as I hoped it would, the shape of the story has clarified. It's a double helix (of course!) and I can see it as sharp and strong as anything. If I didn't know better the vagaries of writing, I'd perhaps feel smug.
Instead, as I know those vagaries all too well, for now I'll just be grateful - for Watson and Crick, the feedback of dramaturg Rob Drummer, and this reassuring flow whilst it lasts.