Read through the entire AP in order to get a grasp on how everything connects in the story. It'll help you figure out which NPC's are important and you should pay special attention to. It'll also let you drop hints to your party and know how to play up the flavor to keep everything cohesive!
Apart from reading the AP over with a fine tooth comb I would have on hand a handful of rumors and of course insults. If you come across anything you don't understand or want to clarify look here on the boards here for an answer or post it if you can't find it.
Get your players the players guide and make sure they understand the situation in the city, between the shadow beasts and the conspiracy theories around they should have a real reason to distrust the government.
Something else I would do is to make sure the players have a root in town, know where in town they live or work before the adventure starts. I find that little tidbit helps to tie them in.
Also.. you might look in here
*edit*and one of my players beats me to the post.*edit