A hint I learned from participating in several LARPs over the course of a couple of years is to tailor the information to the character (and, thereby, to the player).
This was done by a system of differently-colored sheets handed out as part of your character packet. (I may have the colors wrong, but ...) Whitesheets represented single-player-only information (like your character sheet), greensheets represented secret information shared by a small number (like the description and goals of your secret organization), and bluesheets represented information that was common knowledge (like the history of the town the event took place in).
Anyone could read any bluesheet they came across (and everyone was generally given a copy at the beginning of the game), but was prohibited from reading white- or greensheets that weren't their own.
I'm using a similar system for the one-off I'm about to run in a couple of weeks. I've attached a zipped sample of a whitesheet (Char_Defensive_1.doc), a greensheet (Org_Emancipators.doc), and a bluesheet (Org_Warforged_Division.doc).
Of course, I expect that none of the players in my group will read any of these before-time, right?
So, basically, I recommend thinking about what people in the world would know, and placing information accordingly. It's OK to hand only the player whose character is from Strongbadia the Strongbadia City greensheet, while everyon else gets the General Geography and History bluesheet - that way, while you're playing the game, he can chime in with information about Strongbadia that no one else knows. Bonus to the player, who gets to play an in-game expert, and bonus to the DM, who gets to give his world a bit of mystery.