Once you've got an emotional tone for a picture, or some kind of narrative hook or idea behind it, you need to take another look at it. If you try to describe the whole thing you'll run out of things to say pretty quickly. The image directly below here, for example, is a picture of a sunset reflected in a pool, in the middle of some grassland. And that's it. I've blown it now, I've said everything there is to say about it, and I've still got 44 minutes of writing time left.