In the previous post I discussed how you can use dialogue to reveal a character's secondary intentions. Another tool is what the characters wear. Novelists use this quite a but, but screenplay authors often don't--and should.
The two most common messages that people try to send via what they wear are, "I'm high class/rich/important" or "I'm just one of the folks."
Ironically, people who don't have much money spend a lot on clothes that suggest they do, and people who do have a lot of money spend a lot to make it appear they don't (high-price clothes designed to look like those worn by poorer people--but with a label to prove you did actually pay a lot for those torn jeans, for instance.)
The poorer people are sending the message, "Don't judge me for my lack of money," and the richer ones are sending the message, "Don't resent me for my abundance of money--but also don't fail to notice it."
Beyond these broad strokes, people use what they wear to send other messages.
In college I knew of someone who wore Native American jewelry to suggest this was his heritage (I think he was actually Italian, but this got him dates).
Some people wear an item of jewelry they hope will be a conversation-starter (they're ready with the story behind it). Or it might be something they inherited and wear in memory of someone special.
Some people have a wardrobe that is predominantly one colour. For a while, all black was the badge of the hipster, now it's more of a cliche.
Then there's body art. When I was a kid the only people who had tattoos were sailers and the guys who worked at carnival sideshows. These days it's so common that having one doesn't mean anything in particular and you have to have something pretty intense to be noticed for it, but that's an option.
For another character the traces of a tattoo they had removed might be revealing of an incident they came to regret.
Just as dialogue can reveal what people want to communicate beyond the words, so can what they wear, and it's a tool you can use to give the reader subtle (or not so subtle) clues.
(For more on creating characters and crafting powerful plots, see my book, "Your Writing Coach." It's published by Nicholas Brealey and available from Amazon or your other favorite bookseller.)