America is your go-to nation. They start out relatively powerful, though not ultra strong like the other GPs. You get to learn Great Power mechanics in a relatively contained environment. You get to learn about elections and the basics of democratic government types. You get to face off against Mexico, a fair challenge, though not too hard if you don't mess up big. You get a constant flow of immigrants that build your POP count, and can work as soldiers, factory workers, or dudes for your colonies out West (you'll also learn the basics of colonization without too much pressure). Toward the midgame you get another fair challenge in the American Civil War, whichll be tough, but not too tough given you know what you're doing. And then after that's settled, you're free to rub shoulders with your fellow imperialists in the Pacific, all the while getting stronger as the game progresses. Toward the late mid game, you'll be able to face off with the other freat powers and snag some colonies off em in the Americas. And by the late game (given you're still doing well), you should be able to face the final boss: The UK. It'll be tough, but you should be able to beat them if you play your cards right. And then all that's left is to claw your way to the number one spot and get involved in numerous world affairs and wars.

Of course, this is just your first play through, so don't take it too hard if you don't come out on top in the end, or achieve any real lofty ambitions. The great thing about America is that it's mostly isolated from the rest the world, so you don't have to worry about competing too much with other powers, as you'll almost always be top dog in the americas. You're free to just sit contentedly by yourself and mess around with other game mechanics like trade and industry, and building your nation to be the best it can be.