One way to avoid what has already been done is to be true to yourself.
Now I rewrite more and more severely, and I take great pleasure in cutting thousands of words out of first drafts; I think that's a pleasure worth learning as early as possible in one's career, not least because realizing that one can do it helps one relax into writing the first draft in which it's better to have too much material for later shaping than not enough.
Thomas Ligotti is an absolute master of supernatural horror and weird fiction, and a true original. He pursues his unique vision with admirable honesty and rigorousness and conveys it in prose as powerfully evocative as any writer in the field. I'd say he might just be a genius.
I'd forgotten - perhaps preferred to forget - that I'd caved in to the interference of some copy-editor... somebody anonymous whose commitment to finding something wrong would not disgrace an Eastern European clerk.