Have you ever walked into a room, looked around, and come away with an instantaneous first impression of the inhabitant? An impression that may have been modified a bit after meeting said inhabitant, but one that was probably at least partially correct? Welcome to snooping.
Most of us snoop, perhaps unintentionally, perhaps with purpose; with the help of Sam Gosling's book Snoop: what your stuff says about you, you can learn even more about people without even meeting them.
Okay, this sounds like fun, but what does it have to do with writing? First, it's a well-written and highly entertaining book (I missed my stop when I was reading it on the bus). Second, if you know what someone's stuff says about them, you can sneak all kinds of great information about your character's personality into your novel. Your audience will come away 'knowing' the character, but they won't know why they know what they do.
Sam uses the Big Five personality traits in his work: openness, conscientiousness, extraversion, agreeableness, and neuroticism. You can probably identify where people you know fit into a big five personality profile. Extraverts thrive on contact with other people (I think of them as friend-collectors). People who are conscientious buy more of something before it runs out, are punctual, etc.
Now think about the characters in your story. What would their personality profile look like? Does their profile fit their profession? Introverts don't usually make good salespeople, so you may find that you need to rethink your character's personality, so that it matches their profession. Or perhaps you deliberately want to find an unusual combination for your story (the extroverted truck driver who uses his CB radio--do they still use those?--to chat with anyone and everyone on the stretch of highway).
And to add another layer of believability, what would this person's stuff say about them? If you describe a large music collection that contains everything from the Beatles to Mozart to Tool to Lady Gaga, the readers will know (although they won't know how they know) that the character is open to new ideas and experiences. See how that works? Pretty cool, huh?
And guess what? I happen to have an extra copy of Sam's book. I don't need two, so I'm going to give one away! Details will be up tomorrow.
Where do you like snooping best? Medicine cabinet? Kitchen? Office?