Acknowledge everyone's personhood.
When you and your friends choose your characters at the start of a game, you choose to hunt a story about those people and their lives. But all of the other people that they meet have their own lives and their own stories just as eventful and important as the one you’ve decided to track. When you meet those other people, their stories briefly intersect with yours. Show us that these people have their own lives and stories. Let them mention events beyond the scope of our current story, hints and references to a wider world, and an active life beyond what we can see at the moment.