As a writer, I'm sure you've noticed that when you're out and about, people are talking, yet there seems to be no substance in what they're saying. It's as if they are simply parroting what they've seen on TV, newspapers, on the Net, or heard on the radio. This is why good writers are so important—they are a clear voice in the wilderness of false news, cliched responses, and second-hand opinions. This is the reason I destroyed my television over twenty years ago. The detritus of the new world was filtering into my writing, and making it sound trite.
These days, technology has made it even harder for writers to create semi-original work. There is always something getting inside of what we're trying to say...tainting it ever so slightly. I think it's impossible to avoid. Yet, you can limit contact with these sources. For example, if you're writing a science fiction novel, it might be a good idea to limit viewing science fiction movies, or picking up the latest science fiction best-seller until you've at least set down the first draft of your story.
There's no such thing as completely original, yet you can edge closer by limiting your contact with what's already been done. This idea rolls over into the publishing industry too. I know of publishers that specifically say, "No more Zombie stories!" The market is saturated. Serious writers are not here to do what has already been done.
So...my fellow writers...listen to yourself...to the winds howling through the trees of your imagination. Be your own truth, and share it in your work.