"In large measure becoming an artist consists of learning to accept yourself, which makes your work personal, and in following your own voice, which makes your work distinctive."
from "Art and Fear," by David Bayles and Ted Orlando
That's easier said than done, of course. It's difficult not to start thinking about whether the marketplace will want what you create, which usually leads down the road of doing what's been done before, in a familiar style. That, in turn, makes your work less likely to stand out.
Here's a fact that is often missed: If you write something distinctive, something very different from what is out there now, it may not sell. But it will get you noticed, and getting noticed is the key to getting hired or getting people to ask to see what else you have written.
What if you're not sure what your voice is or should be? It's not something you decide. It's something that emerges when you write a lot. It may be that you're the last to notice it because it's so natural to you.
Beware of books and teachers who try to "smooth out" your writing. They are not your friends.
I'm not suggesting you shouldn't learn the craft of writing. You absolutely should. But once you have mastered that, let the story itself and your intuition play a strong role in shaping what you write.