Depending on the art style and limitations, you can get pretty crazy with body types, limb proportions and head shapes to detail a person's character. Having an original and particularly unique silhouette is useful for setting a character apart from others. Buff muscles and sturdy build can show one's strength and will. A pudgy build can imply sloth or carefree personality. Broad shoulders show manliness, whether literally masculine or implied. Soft features for meekness. Body language can tell a lot about a character too. Universally, however, the best character designs concentrate on the face moreso than anywhere else though. The shapes of the eyes, jawline, nose, mouth, etc. and their size relative to the others can assist in portraying a character personality traits. Blush for innocence. Messy hair for messy people. Maybe a big shnoz to imply they're literally nosy. A sharp square jawline can portray a character's rigid ideals like a military general. An evident under-bite, making someone look like a primate can suggest low intelligence. Maybe a squint in their eye might imply that they're near-sighted, probably wears glasses and therefore smart or ditsy. The space between one's peepers can show a lot as well as the distance between their nose and mouth and ears.
Facial hair, clothes, visual props and body language are also important. There's a lot of factors in designing a character, even some you might have thought about. in Asian cultures, the shape of one's head and jawline heavily suggest their personality. Rounder heads and faces are said to be calmer while rigid square shapes are stern or strict. There are other -non visual- hints you can show to suggest a character's personality. For instance in Japanese culture, a person's blood type is said to tell you their personality as well as the colors they wear or (in the case of recent manga/animation) their hair color. What do you think of when you see a blonde woman, hm? A red-head? Those kinds of archetypes may be unique to western society but there's tons of other examples out there.
-Or just work backwards. Think of the most stereotypical of whatever archetype you can think of, pick a facial or physical trait and go nuts. imagine another character that fits whatever traits you want -preferably a caricature of sorts-, pick a visual aspect of that character's appearance and run with it. Again, though, it all boils down to art style and limitations within that style. There's TONS of resources you can find online for designing characters. Most of them are going to suggest the same kinds of things i just did.
