How do Japanese comic (manga) covers typically convey genre and target audience?

Manga covers use visual cues to signal genre and target audience. For example, shonen manga (aimed at young boys) often feature action-packed scenes and strong, heroic characters. Shojo manga (aimed at young girls) tend to have more romantic and visually delicate designs with attractive characters. Seinen and Josei covers, targeted at older male and female audiences respectively, employ more mature themes and sophisticated art styles.