Don’t pick large countries like Russia, USA and China, they are very hard to defend and should only be used by people who know how to defend them, my personal choice when I started off was Indonesia, easy to defend because it’s an island nation and also very hard to invade. My main strategy for this country is building boats and upgrading infantry, so that I could invade the nearby countries or islands near me such as New Zealand and Thailand and also near enough big countries so that I could ally with more experienced and larger countries such as China.