By far the most common entry-level mistake in the writing game, the thing that can get a perfectly good story rejected by an editor on the first page, is overwriting: a writing voice that is laden with energy and adjectives, that tries too hard, that is self-conscious in a way that detracts from the story, that is obviously the work of a writer trying to poeticize a story that doesn't stand a chance.
Bad writing voice is like wearing a clown suit to the Oscars. Chances are you won't make it past the lobby.