Early, Expert

I think it is best to clobber the French from turn One and never stop until they are eliminated. Why? Just because they're there, and you can, and the money is great. Start with Brittany (isolated) and Flanders (commercial and strategic hub).

You will of course be excommunicated.

The ensuing Spanish invasion in Aquitaine and two Spanish Crusades (the first into Aquitaine, the second into Toulouse) are good training grounds for your generals. You don't get many high-ranked generals (in France or elsewhere) and since the English Princes are a pathetic lot you need to work on some star generals against serious armies. After that, Aragon and Navarre are cake.

Wales (bribe) and Scotland (four Town Watch + three Archers out of Northumbria will do the job) take care of themselves.

Never ever lose sight of Flanders which will be the strategic (geographic as well as financial) bottleneck of your campaigns.

And hey, conquer the world before High is over. It's been done before.