Many fantasy campaigns have a static world. Nothing significant changes in the world around the characters. I like to thrust the characters into situations where the world significantly changes. For example, in my World of Tiglath campaign the entire government organization changed almost overnight.
Characters must make new connections to the world. Who they connect with and what they do in the world has consequences. This requires defining the relationships between the non-player characters. The Game Master should lay out the network of relationships from the lowly fence all the way to the ruler. This way, when the players sell a little bobble that has some importance to a high level official there is a network diagram showing how the official will learn of the transaction. In the movie The Usual Suspects, Kobayashi tells each character how they unwittingly stole from Keyser Soze. The Game Master should plan for that type of scene. The Game Master should keep track of everything the player characters do. That way, several gaming sessions later the Game Master can ask the player, “Do you remember when you sold that strange looking piece of amber to the fence, Spezoil?” Then when the player character is confronted by an official who pulls out the piece of amber and says, “You sold this to my informant, Spezoil. How did this come into your possession?”
The news is full of stories how people come to power and fall out of power because of personal indiscretions. When the players find some minor trinket they have no idea the trinket could have a political history that could cause political upset. In the book Johnny Tremain the main plot revolves around a silver cup engraved with the Lyte’s coat of arms. Game Masters should learn to steal good plot points. The party recovers some loot including an engraved silver cup. Houses can rise or fall depending on which fence gets the silver cup.