Since this is your first time playing EU IV, Welcome
Two, as first time player taking on France and winning 3 times is fantastic. First time playing I chose Castille and France kicked by butt big time, So congrats on game
Three, I beat France with choosing Terrain and river crosses as my friend, I choose when to have the war, Always when they are at war with somebody else, (given time France will get into a major war) and I bring in an ally, Burgendy, Austria.
One of my favorite time is during 100 years war if I can ally Burg, or Austria or both and attack them ( but Aragon may backstab you ). Yes, i go into debt due to letting Mercs take alot of damage first. You dont pay maintence on nonexistant troops.
Timing on when you chose to attack is important, if early I go for admin idea group ( name forget ) that offers 1st idea that reduces merc cost and third idea reduce merc maintence cost.( 2nd idea reduces coring cost by 25%) so good all way around.
if attacking later have a mil tech is recommended ( this one always debatable ) but Offensive offers March as last idea. Ultra nice to stack wipe or save your troops with reinforcement Now. Never take mil idea as first idea group as first few mil techs are to good to pass up.
If the Burg Inheritance fires, Austria can handle a lot ( not all from my experience) of France. Very good anti France Call to Arms nation. My best success's are with allies Portugual, England, Austria.
When my goal is to destroy them, I always release vassals and nations over taking lands. I can take their vassals land later. Goal is to reduce their insane manpower and manpower recovery speed.
As said by others before, bait them into attacking in the mountains with your army size big enough to survive, because you cannot have your reserves attack until 1 day before frances troops arrive or France will stop their troop advance. Savoy is another area with mountains that is good to bait them to.
Since this is your first game and with 3 france wins under your belt, I am expecting you to write this soon
