In Structuring Your Novel From Basic Idea To Finished Manuscript by Meredith and Fitzgerald I came across this bit of advice. This is something we all know but often we don't think about. The general parts of characterization. Some of these traits we don't think about but often use them.
Universal traits - Male and female. Sure when devising our characters we think about the hero or heroine or villain as to their sex. Sometimes we forget this when drawing the characters. Men and women react differently emotionally to events. Their dialogue tends to be different. Not always but women tend to use longer sentences than men. But also remember there can be exceptions.
There are National traits. Much depends on the country where the character was born and raised to give hints to their personality. This may be why when I'm writing contemporary I tend to have my characters as from the US rather than from another country. When writing fantasy I have to develop the country and fit the characters to that country.
Regional traits - Different parts of the country have their differences, especially in language but also in reactions to events. My characters tend to be from the middle Atlantic States where I was born and raised. Even here since moving to various places in the country and living there I've found differences in traits so I can have a Texan or a southerner. I've lived there and observed.
These are the first three and I'll look at the other three next week.