I've said before that writing for a living is a not for the risk-averse. We gamble with every book, every proposal, every plot, every character -- sometimes it feels like every word. 'Cause if your editor and your readers don't like it? Your career is going to suffer.
But there are varying levels and kinds of risks you can take in the writing biz, some more risky than others.
There's the Big Risk. This is the one where you really go out on a limb. You try something totally different from what you, or anyone else, has done before or is doing. Why would anybody do this? To stand out. To break out. To move up. To sell. Or because you feel compelled -- the story and/or characters have grabbed you and won't let go. Sometimes it's a combination.
Sometimes this works (you sell and sell big-time), sometimes it doesn't (you get rejected or your book flops). Sometimes the result if a mixed bag. It gets your foot in the door, but then the general public isn't so willing to try something new, or the journey between great, innovative idea and execution of said idea falters along the way.
We hear about the big successes, the gambles that paid off. The writers who did this and got the brass ring are there to remind us. We don't hear about the flops, because those writers don't talk about it (and why would you?) or they go on to a different career.
Then there's the calculated risk. You try something new, but not too different as to make readers unhappy or dissatisfied. This can be called "putting a new spin on the tried and true" or perhaps you take a chance with a different kind of character, or maybe it's simply your unique voice that people like.
This is my usual brand of risk-taking. It keeps things interesting for me and hopefully my readers, but doesn't put my career in jeopardy.
Unfortunately, I think too many unpublished readers try for no-risk-at-all. They imitate the best-sellers, and try to figure out exactly what the market is doing and where it's going. If only they can find that magic combination that other writers have used, they'll sell. Either that, or they go WAY out on a limb, writing the "book of the heart" which is all well and good for satisfying one's creative ego, but may mean the book appeals only to a very select audience.
If I had to advise an unpublished author on one of these two approaches? I'd say go out on the limb, because if nothing else, you'll have satisfied yourself. And on a more practical note, I think your "writing voice" will be the stronger for it, so if you go to the Calculated Risk, you'll have something "extra" right from the get-go.
How much risk a writer is comfortable with is one of those things every writer has to come to terms with over the course of his or her career. And like so much else, there's no right or wrong. It depends on a whole host of factors unique to every writer. The one thing we all have in common is that we're willing to risk sending our work out into the big wide world in the hopes that it will (eventually) get published.