Original review below. I can't suggest this game with $352 dollars of DLC; thats ridiculous.

The first thing you should do is go to YouTube or to the EU4 wiki and learn about the game first. Put in a few hours on the Wiki and a few weeks on YouTube to get the basics on playing Castille, because that's probably going to be your nation for a few tries before you don't get wiped off the map. A bachelors or better in European history would go far, as would a Masters or a Ph.D. Personally, I recommend at least a Ph.D, because that shows the amount of committment required to play EU4 and have any real success in the game. I imagine some time spent visiting the Iberian Penninsula would not go amiss, some time spent studying maps, the lay of the land, sampling local culture and the like.

And prepare to be frustrated when the ledger says that Ottawa (The nation you've decided to test out the DLC with) has the second-largest army in North America and ends up getting their entire army wiped by the least powerful nation in North America.

EDIT: OH wow, I was dumb back when I wrote this review. It's a difficult game, but with some care it's pretty easy to accomplish your goals provided that you don't bite off more than you can chew. Absolutely a game where having the wiki open or some powerful friends wouldn't go amiss.