Tremendous advice from The Alexandria echoes what other folks are saying here: Don’t Prep Plots.
Basically, prepare scenes and think of what is going on outside the frame (basically, what are the NPCs and factions up to while the players enjoy their shopping trip?). That helps you avoid overthinking it and wasting prep time. It also makes the world more responsive to player actions.
I have a piece of counter advice that allows you to on occasion plan a plot point. Generally your PCs are most invested in their beloved NPCs, either from backstory or the plot you’ve developed. If you have a cool idea, these NPCs can often be inserted into it and offer exactly what the players enjoy.
That’s a great idea. The players have invested in the NPC, so make that pay off by involving them in the story.
