Historically, French blue shirts are not a "classic" look.
I like to follow the guideline of light shirt, darker tie, even darker suit.
(Casual and summer clothes excepted.)
I personally associate French blue shirts with late 1990s style--as mentioned above, black trousers and black square-toed shoes...we may as well throw in a big black belt with a designer logo buckle to complete the ensemble. Oh, and don't forget the white necktie!