A human wakes up at the bottom of crater in the middle of a wasteland. He has nothing to his name but the clothes on his back, a half-crumpled pack of cigs, a cheap lighter, a small notebook, a ballpoint pen, and a flask of most-likely illegal moonshine. Also, he can't seem to recall who he is, where he comes from, or how he arrived in the desert in the first place.
It might be from the blunt-force trauma of falling out of the sky, but he's not quite sure about that.
What he does figure is that he's no longer on Earth. The creatures popped straight out of a children's fairytale book, pastel equines who are way too cuddle-happy, and a rather ornery goddess of the night pretty much clinch that notion.
So what's a lone human with no viable chance of returning to a life he can't even remember to do?
Creating a guide so that he can survive the foreseeable future seems like a good start.
"There are three immutable facts I've come to embrace since my arrival in Equestria - narrative causality is king, magic can go eat a sack of horseapples, and Vinyl Scratch is rutting insane." - The Human's Guide to Equestria, Foreword