One of my absolute favorite commercials is Google's “Parisian Love.” It tells an incredibly sweet story without showing anything more than a series of Google searches. Yet it's so effective because we're wired to search for the connecting factors. We're good at filling in the details.
Have you ever seen a collection of photographs that tell a story? If you saw three shots, one of a girl posing in front of a pool, the next of her little brother sneaking up behind her, and the third of her splashing around in the water, you would probably have a pretty good idea of what happened, even if you hadn't actually seen her brother push her into the pool.
So what does this have to do with writing?
Well, often the characters that we're writing about are absorbed in their own situations and might not be very observant of the other people in their lives. But just because a POV character isn't keeping up a running commentary on the life and times of every friend and neighbor, that doesn't mean the reader can't be allowed to see glimpses of the stories happening to those minor characters.
For example, a POV character could find out that one of the major industries in her town is laying off several hundred employees. Then maybe she drives by a neighbor's yard sale a few weeks later and considers stopping to look at the nice TV he's selling but decides against it. And then maybe a few weeks after that she sees that the sports car in his driveway has been replaced with a beater. And perhaps after a few months there's a foreclosure sign on the house.
The character doesn't even have to know the owner of that house for us to get a good picture of the story happening in this neighbor's life. The POV character may not even think about the tragedy unfolding for this neighbor, but the reader will notice and feel that the book has an extra layer of authenticity.
So if you're struggling to bring some extra color and life to your book, consider the stories happening in the periphery of the main plot and try to come up with a way to slip those other stories into the narrative.
Do you have any minor characters who have been giving you trouble lately? Could you liven them up a bit by given them their own stories?