Might I suggest writing something original and posting it for critique? The problem with fanfiction is that you're dealing with established characters in an established world and established mannerisms with a bunch of 'canon' knowledge you can typically assume your audience knows.

You don't always get that in original fiction. I saw your post on original fiction ideas, but that was about it (granted I'm joining the game fairly late). From what little of your stuff I read I've gone "Nice drabble, okay dialogue, not a whole lot of action and the dialogue can sometimes seem forced to fit characters that my perception says wouldn't speak that way' - none of which have any bearing on you as a writer, your writing style or any 'right' or 'wrong'. I guess you could say I want to see a world you create, its characters their interactions and their stories. Once I see how you describe and bring us into something completely new I'll be better able to comment on your writing, because at that point pace, information overload, exposition and all that crap become relevant.

Oh and you can public this at the risk of having your Yorkshire/fandom friends tear strips off me :)