After creating an adventure, or reading through a pre-made adventure, think about how you can add more spice to it. It’s fun and your players will enjoy it. I personally prefer to leave as many loose ends as possible lingering after an adventure and seeing where they lead in the future.
One way of doing this is to use brainstorming techniques, such as listing out all of the major NPCs in the adventure and then thinking about their past, their family life, their affiliations, etc. Branch out from each NPC as much as you can to give yourself plenty of things to toss in to the current and future adventures. Even if the NPC dies, they can linger in future adventures through relatives seeking revenge, maybe they mentioned something about their past before they took their last breath…the possibilities are pretty endless.
For an example, I was running the Plot Point Campaign for SteamPunk (a Savage Worlds setting by Reality Blurs) and I decided that one of the NPCs gets killed, which opens up dialog with a grieving cousin later on. I also decided that one of the major villains of the scenario had an older brother who wouldn’t be happy if the PCs killed his sibling. And then I decided that if the older brother’s quest for revenge failed, the PCs would catch the attention of the two’s crime boss. In exchange for not killing his enforcers, he supplied the PCs with very nice living arrangements and mostly legal work.
Why spend all that time on an NPC just to use it for one adventure? Think about who they would know, how they would interact with the local population, and even if they do not directly interact with others, how do others perceive them? Do they have distinguishing features that cause them to stand out in the minds of the people? There are so many possibilities to expand your NPCs to the point of almost being able to create adventures off of their histories/connections/influences.

