
Mind you that after the civil war is over, you don't really have anything to do because your army will be half depleted and your country will be ruined, and next door is France who is much better positioned than you at the time, and Portugal who has so many colonies that you won't get them to surrender by just taking the mainland. You can also learn about volunteers and lend-lease. 3- Spain because you can only really learn combat by fighting, and the Spanish Civil War provides a great oppotunity to do so. You also learn about bad terrain because of the Andean mountains and the Amazon jungle. 2- Peru because it starts off fascist in South America, so you can easily DoW Ecuador, Chile, Bolivia and Colombia and get a feel on what it's like to go for massive expansion with little resources and factories.

You can learn about navies with it considering you have hell of a position on the mediterranean. 1- Turkey because it starts real close to the conflict and can ally anyone and have high hopes of victory regardless. Best nation for a beginner? Hands down Germany.
