I would suggest "The Even More Flexible French" by Moskalenko.
This is under the assumption that you are not a pure beginner at chess, and understand general concepts about pawn chains and blocked positions, like attack a pawn chain at its base, and when the center is blocked, attack the side in which the blocked pawns point, and so in the French, that is Kingside for White and Queenside for Black.
It is not an easy book, and you have to be willing to spend about 60 to 90 minutes per game (just over 100 games in the book), but with the effort (it should take you 3 to 4 months if you put in 90 minutes a day on a daily basis), you will be a better French player.
I’m fairly new to the French, maybe 5 otb games. and I’ve decided to build a repertoire. Should I start learning the classical or Winawer first? Any repertoire book recommendations? Any general advice about the French?
I’ve never had a real repertoire. I played the Sicilian for many years with good results, but I’m wanting something new.