China is the most fun to play. No navy, fast turns. Trade everything you can to your friends and cash-rush light tanks and artillery. Don't keep too much cash in the bank, the Japanese will steal it when they capture your cities. Try to take one of the Japanese cities up NE (can't remember the name but it's an army there) - a broken line for their troops.
Edit: you need plenty artys to capture that city. Moron AI will probably only move two units into the army. Soften up and move in for the kill with your light tanks.