What I've noticed is that about 80% of story writers don't have a plot. When they don't have a plot, they also forget to create characters that matter. This leads to quick, graphic exposures of events that are so anti-personal that you can really give a rats ass about reading it. Amazingly, this being the only thing the person is capable of, these particular stories are also unimaginative in the midst of their pure mindless gratuity (not that I'm begrudging gratuity).

I'm left thinking, gee guys, I could have written a shopping list of THINGS and skipped the disguise of a story, omitting say ... ... ten or so words.

Do you need an outline? NO. I often just write with an idea for the characters and a bit of a notion of how I want the character moved through the story to some vague ending. Then I let the magic work as I see my people interact. Others create outlines from the start, a very valid approach. But, when done, the reader shouldn't be asking, "Did that writer even have an outline?" That's a fatal review.

So, having said that, here are some rules :

1) Every story has to have characters that the reader can relate to. Win or lose, we have to care about what happens to them in order to care about the story. This takes a tiny bit of work.
2) If I've read exactly it a billion times before, why write it again? Can't we have one little biddy twist, for crying out loud?!?
3) Any story that doesn't have a plot is not a story, by definition.
4) Make dialogue that both counts and is believable. "Oh, I'm being skewered with a stake! This makes me so horny!" Right.
5) The best horror has the lowest body count. Consider. This might mean that it has more to do with how you go about saying it than how many knifes in the back one accumulates. One is a story - the other is a cartoon.