Across the vast and glorious interwebs, aspiring writers can find all sorts of information and advice on what to write. We can track trends, see what's selling, read opinions on what will never, ever sell, what has sold too much, what the next big thing it, so on and so forth. And while this information is interesting (take Alexandra Bracken's [a debut novelist who also works in publishing] intriguing recent post on trends she's seen), I'm not sure how much you should worry about it.
And if you were to tell me that you wanted to write a book set in WW2 Germany, focused on Germans, with Death as the narrator who tells us from the very beginning what's going to happen?
HA! That'll never work.
And don't even think about trying to write a book with vampires, faeries, or werewolves. The market is saturated and there's not room for anything else.
So yes. Clearly there are FOOL PROOF formulas for success out there.
Oh, who are we kidding? No one really knows what the next trend is going to be, or what trend is dead or too saturated. So here is my advice, for what it's worth: write the book you want to write. Write it how you want to write it. Don't chase trends or try to make your book "the next [fill in the blank wildly popular novel here]." There is no single idea out there that is a guaranteed sell. I've talked about this before, but I firmly believe what will sell is a) your work and b) your voice.
If you're trying to force a novel that fits into a hot trend (and by the way, I hear that forbidden romances between leprechauns and yetis are the next big thing, but you didn't hear it here), it probably won't have that special something that a story you come up with on your own and are passionate about will.
So here's to being original, regardless of whether original means a new way of looking at a popular subject or coming up with an entirely new type of novel. Trends have to start somewhere, right?
Now if you'll excuse me, I've got a hot, hot yeti-leprechaun kissing scene to write. "Just bend down a wee bit! I can't reach yer great fuzzy lips!" "Rrrrnnnrrrrowwwlll." "Yes, love, ye have me heart, too!"