The Chick Lit genre, appealing to adult females, usually features a young female (attractive and successful) dealing with relationships, careers, friends, family, and so on. The tone is usually pretty light and humorous. When looking over the common book cover tropes, I found the following trends:
Illustrated - lots of illustrated female silhouettes, shopping and purses, and dresses
Bright Colors
High Heels/legs
Girly/script font
flowers & hearts
Lots of pink, red and tiffany blue, pastels
...pretty much illustrated legs in high heels.