Especially if you're a woman. French women only wear short and long skirts or very short shorts in hot weather. Jeans shorts I've only seen on Americans. They wear leather sandals, without socks.
Women also wear leather sandals, generally with heels.
In colder weather men and women wear leather shoes. It depends on the restaurant and event, of course, just as in the States. For women, the general rule of thumb at dinner in restaurants would be no jeans and no sneakers. Anything else is fine, depending, as usual, on the event. Generally they wear comfortable, nice blouses.