I think it must be very difficult to do in short story situations (I don't really do short). You are reliant on what Stephen King calls the telepathy between writer and reader - you create characters that the reader will understand and relate to because they see something in the character that they know from their own life (and/or reading). To do this without creating stereotypes is difficult, even in longer fiction. In short fiction, children's fiction, and with minor characters in longer fiction, it seems to be necessary to mark a character, often exaggerating some aspect of them - whether that mark is visual, speech or other idiosyncrasy - and then referring to that mark often enough to have it stand out (without being annoying). That mark may be stereotypical to some extent (it's hard to avoid), so you provide other details of make the character more unique, but it is the regular references to that mark that keeps reminding the reader of the person and their nature - that is; it's best if there is something about that mark that relates to their nature.
Or that's the way I see it. I'm not an expert, I just like replying to threads like this one because it makes me think about my own writing and question how well I do what I think I know. (If that makes any sense.)