Ceidleh is right on re what to wear, except when on the topic of shoes I think one should note the average Europeon , while not on holiday, does not walk 10 - 15 miles a day , like a tourist does, so therefore disregard what a local wears when it comes to shoes. Wear comfort.
Also, last August , for my entire 9 day visit, it was cool , and rainy many days, never had to turn on the a/c once, and hadn't brought enough warm clothes, was sick of wearing the one pair of long pants and jacket I had brought, every day, .
I had of course counselled my travel partner to " pack for the heat, light skirts, cool sundresses, etc,, boy that was a mistake, even though every other summer I had been to Paris it involved roasting to death, LOL