Perusing the shelves for Dungeons and Dragons Third Edition books? If you've come across the Stronghold Builder's Guidebook, I've got some advice before you buy it. Especially if your group isn't hardcore into that system.
Riches don't consist strictly of coins. Don't gloss over all wealth as money – instead, view it as a way to enrich the verisimilitude of your campaign world. Add some complexity to those hoards! People can be rewarded with items, service or land just the same.
Threading any given object or NPC into a campaign means that it can be destroyed by the party. Never introduce anything in the hopes that it won't be trampled underfoot – no matter how unlikely that is. How then does one create a secret organization within the world the PCs occupy?
Portraying the rest of the world surrounding the party can seem quite the daunting task. You don't want it to seem dull yet you might not know who the characters will interact with. Instead of crafting each person or assuming people insignificant to the adventure are the same, make “types.”
While brainstorming is great for jumpstarting your imagination, creative meandering can detract greatly from your session preparation time. Creativity shouldn't be kept to a strict schedule, either. Here's how to make sure you have what you need prepared with limited segues.
You know that campaign you put so much work into but it never got to finish? There's that wonderfully epic battle waiting for the party, but each of the players have all moved or aren't game to play anymore. If you can't reuse it, recycle it into it's own fictional work.