From my experience playing Axis and Allies, I have found out that you can't always rely on certain army builds and situations because who knows how the dice will roll or what the enemy player will do? but here are the general builds that I use which usually win me a few games.
Russia: 8 infantry (4 in Russia, 2 in Caucasas, and 2 in Keralia)
Germany: 2-4 infantry, 2-4 artillery, 2-4 tanks, and usually a naval or air unit if you don't spend it all on land troops (all spread as evenly as possible between Italy and Germany).
Great Britain: 1-2 destroyers in the Atlantic navy and the Indian ocean navy, 1-2 infantry, 1-2 artillery, 2 tanks (almost all of the land units go into the India base)
Japan: industrial complex in French Indochina, 1-2 destroyers or 1 cruiser, and any IPC's left over is put into tanks.
United States of America: 1 infantry or tank in the West coast, everything else into another battleship (for the east coast) and destroyers, any IPC's left you use for transports.