More by one of my favourites, Susan Morris, on the easy bit (Inspiration) vs the hard bit (turning it into a plot):
But the next part—turning it from idea into a plot? That part’s why so many people hate outlines. Inspiration is easy because it’s unlooked for. Plotting and outlining are hard work, even with the best of ideas. But there are some tricks that can make it easier. Here are a few techniques to play with the next time you want to try to wrangle that flash of brilliance and turn it into something storylike.