I had lunch today with a friend who wears rings on her toes - one on each foot. She told me that someone recently asked her if she was Indian (she's not), because apparently there is a tradition involving wearing one toe ring on each foot if you are a married woman. This isn't a tradition I'm familiar with myself, but I do have a necklace my mother brought back from India, which my mother told me is a "married woman's necklace."
This kind of thing provides terrific evidence of the fact that even the smallest things can be judged significant in people's lives. A man's earring worn on the right ear versus the left used to have significance in the gay community. The closing of a kimono left-side first or right-side first can be significant, or the way you pick up a teacup.
In each case, the significance of the object or act is in the head of the character doing the judging.
This relates to my post of yesterday, inasmuch as characters can be differentiated by the way they judge situations. I find it fascinating to write a conversation between two people from two different cultural groups, and to switch point of view halfway through, so that readers can share the difference between what the two people notice in the interaction, how they judge the significance of one another's clothing, posture, etc. The most fun for me is when the two don't understand each other because they can't entirely back off their own cultural categories and judgments.
Individuals can also have different ways of judging. Imagine the way that a detective looks at a room, compared to the way that a child looks at it. Each will be looking for different things, putting importance on very particular and personally relevant details.
And then there are the characters with extreme, or impaired, judgment. This is where psychology comes into play. When I write a character as simply mean-spirited I find I don't know where to go; I'm grasping at mean things for that person to do. When I go into their psychology to identify a traumatic event that has changed their judgment, or even to identify a mental illness that alters their perception and judgment of events, it has a wonderful effect: it ties down the driving forces behind their behavior. Suddenly their behavior is no longer random, but principled, and I can take their strangeness much further without straining credibility.
I'd like to add one last observation that comes from the "show don't tell" arena. Having a character with a complex cultural background, or a mental illness, doesn't mean that everything about their culture or judgment has to be explained. They can demonstrate it in the kinds of things they treat as unremarkable, or where they suddenly take offense. Even an offhand descriptive adjective can be turned toward illuminating their point of view. I've even gone so far as to try to build the mental characteristics of a character into the prose style I use to write their voice. I'm thinking in particular of an obsessive-compulsive Machiavellian character I'm working on, who has a tendency to fixate on a topic and return to it over and over in his thoughts, always judging things instantly and never questioning himself in any way.
I'll admit here that I have trouble writing non-chronologically. The trick is, I really like the feeling that each chapter will be different because of subtle changes in character viewpoint that grow out of the character's experience.
In any case, character judgment and psychology are productive avenues to explore, if you haven't already.