Likes:

severitus' challenge fics
harry snape friendship fics
dark harry
slytherin harry
artemis fowl fics
lead character betrayed and embittered fics
I used to like Sirius. Now he is dead to me. I also like Harry, Snape, Filch, Ron, Hagrid, assorted Weasleys, blah, most of them. Lupin's boring.
Dramatic irony

Dislikes:

I do NOT like slash. I don't hate it - it just doesn't appeal to me. Though some slash fics are hilarious, I'll admit that.
Out-of-characterness (a little is ok, a lot isn't)
Mary-Sues. No one likes a Mary-Sue. Or self-insertion. Alas, I've found myself doing this before.
Draco. Draco is just a little twit. Speculate all you like. He's just there to glower and get in Harry's way.
Blaise, Pansy, Hermione/everyone except Ron, evil rapist Lucius Malfoy, Draco/anyone

Books You Should Read:
Artemis Fowl, Harry Potter, The Thief, and, The Queen (and King) of Attolia by Megan Whalen Turner, The Discworld Series, Sabriel and others by Garth Nix, Deltora Quest by Emily Rodda (my little sister loves this), Herodotus' Histories, The Count of Monte Christo, The Scarlet Pimpernel, Scaramouche, LOTR, Blood and Chocolate, books by Robin McKinely, books by Diana Wynne Jones, esp. the Dalemark Series, Confessions of Georgia Nicolsson, the first three (and no further) of Robert Jordan's Wheel of Time Series, Crown Duel and Court Duel by Sherwood Smith, books by Tamora Pierce, Pride and Predjudice, Jackaroo, Princess Diaries... ok. I'll shut up now.