General things I like in stories:

-Plot (but I will occasionally read a nice one shot)

-length (I'm at my happiest when I can read a nice plot that already has at least 80-100k words written)

-Good characterization of already existing characters

General things I don't like:

- Authors who write twins (mainly the Weasley twins) as people who just alternate speaking. It doesn't work that way and these scenes make me cringe. They can even kill an otherwise wonderful story for me.

-Bad grammar/spelling. A few mistakes here and there, no problem, we're only human. Several in every paragraph, I stop reading.

-Long author notes drive me crazy. I'm talking about the ones where people will respond to their reviewers for almost half the chapter length. This is silly and they should just send personal messages to these people. Oh, and while I'm talking about author notes...

-Author's who place author notes anywhere mid chapter. It's distracting and typically ruins whatever (possibly) subtle refrence/joke you were going for.

-Dialog that goes on for a long time without reaffirming who is speaking. Also drives me crazy. I have no frame of reference to these two (and sometimes more) characters' body language and while I know it is a commonly accepted practice to use this for dialog heavy scenes, I more often then not find myself losing who is saying what after more then 3-4 lines. To say nothing of the people who use this for page or more sometimes.

-Too much description or thoughts between dialog. I'm not talking a few sentences. I'm talking several paragraphs of inner dialog that takes me so far away from what was currently going on in a scene that I will often have to re-read what was last spoken to remind myself.

-Cliche Overload. I like some cliches in stories because it makes the story interesting but if there is too much, it makes the story very painful to read and i end up not finishing it.