Step 1: Unifying France

Your first step as france should be to unify the provinces in modern day france via taking the rebel settlements of Dijon, Bourdeaux, Rennes, and Metz if the HRE doesn't beat you to it. It might also be advised to take Burges and Antwerp to get the benelux under your control.However, there's still a big red annoyance in your way: England. As long as they're in that castle in Normandy, they will keep popping out troops and will be a bit of a pain once they attack. My sugguestion is to ready your forces and launch a preemptive strike. Invading the rest of England is optional if you don't want to head across the channel but remember; It's not as hard as it was back in the 19th century. England doesn't have a huge fleet.