It's been years since I've really sat down and written like a full erotic narrative, but what tends to get me going is not so much writing the content, but sharing it. Letting someone else read/listen to it. I used to carry around a notebook and my mp3 player and I'd let woman pass them around when I was hanging out at the local bar. If I didn't end up going home with someone that night, the look on their faces, they way their breathing deepened as they read it, how they'd look at me afterwards all flushed and heated... All that would be flashing through my mind as I lay in bed getting some me time.