Here's a little secret: Sometimes I have absolutely no clue what I'm going to write about when I sit down at the keyboard. None whatsoever. My mind is a vacuum - literally. It sucks up whatever it's given, puts a spin on it, and deposits it on the page.
Input - that's the key. When there's nothing worth saying already in my head, I find a random prompt - the above picture, for instance - and see what it says to me. I analyze it for deeper meaning, filter it through my world view, and store it here for you to read, or ignore. I like to think that this practice makes me a better writer. If nothing else, the mental exercise is good. Too often we seek to escape thinking about things, when the only way to add something worthwhile to the picture is to do the opposite.