When an adventuring party goes out to a dungeon, they may learn who built the dungeon and what they are after, but they rarely plan for it. They don’t try to get the right tools, other than possibly getting extra rope if they know they need to repel to get into the dungeon.
But in an urban adventure, you not only have the time to plan, but you should be forced to do it. You also have the ability to choose when to attack. Not putting in this extra effort is foolish. It will likely involve people in the mission (battle) that you don’t want there. Like who? Well, innocents, the police, or battle ready neighbors who may think you are after them as well. So how do you choose your battles? Through information gathering.
Let me draw a contrast between how information gathering is done in Garnock and Forsbury to show how this can work. In Garnock, they are watching their own people, while in Forsbury they tend to watch the travelers who come into town. Because of this, in Garnock they rely on street informants like street vendors, street sweepers, and even street walkers. Meanwhile in Forsbury, they rely on the cab drivers, bartenders and most of all, the bellboys in the hotels.
But how does a party get this information? There are really only two ways. The first is the best way - by having the PCs already have established contacts in town - people who know them well enough to trust them and share gossip and other information. The other is through bribery, most commonly through bribing an information broker. Information brokers are the people who make their living by having already gathered all the information that people are probably looking for, or they know who to go to. But it is important to remember, that very few information brokers are freelancers. They work for someone. So whatever the party is trying to figure out will be reported upwards.
Honestly - I suck at bribes! In real life, I never know how much to tip a maître d' for a good table, or any of that stuff. I’m probably too much of a rules follower. But in game, GMs need to understand how much of a bribe is required. Here’s the only way I can figure out how to do it: Take a guy like an information broker. How many customers does he get in a day? He probably averages one per day, so he’s learning everything he can just to inform one person. This guy wants a full day’s wages to share his information; otherwise, he’s going to go broke. So for relatively public knowledge (info that could be public for anyone who had the time to do the recon), he wants 12sc. A bartender on the other hand who has a job and gets info requests three times a day (on average), he’s maybe looking for 3sc (x3 customers equals a full day’s wage for him).
But what if it is not public? Well anything that could get the broker or his informants in trouble is worth a lot more - probably five times as much. This includes things like who did the merchant leave the sleazy hotel with - gossipy stuff that isn’t public and probably shouldn’t be. For something that could be dangerous, as in tell me the right time to assassinate the target, something that could get the informants involved in a murder, now we’re talking about two weeks’ pay or say 250sc. Why? Because first of all, the informant is going to lay low for a couple of days in hopes that nothing blows back on him, plus if he is in danger, he deserves a lot more. How much do you have to bribe him to keep his mouth shut while the enemy is getting ready to torture him? Yeah, that number doesn’t exist. These guys are not the ones you rely on with secrets!