this is what I would do.
japan- for your first turn, buy 3 tanks & an artillery. on your second turn you should at least have 30 something dollars, buy 5 tanks and whatever you can afford. on your third turn you SHOULD have 40+ dollars, buy 2 destoyers an 2 subs for the rest of the game.
summary- use the tanks to invade china, you’ll need them. spread your infantry out in china to where you use 2 infantry and a tank/fighter/or artillery to take those pesky countries and use the infanrty as casualties. with the subs and destroyers spread them out in the seazones that way us or uk cant run through you waterways. also try to take out as man allies in the first turn, even the us aircraft carrier in the lower right part of the board. and if you can, send some of those tanks in indias direction!!
united kingdom (india)- this is simple, just buy tanks. and use them aggressively!! hold the burma road!!
united kingdom (australia)- try to gather all remaining british naval units together and just build destroyers or subs.
summary- you arent gonna have alot of money to spend if you are playing a good player, so spend all your money. there is no time to waste!! try to get your territories back with britain, those islands are worth alot!! and finally, hope for good dice rolls!!
united states- for the first turn just buy 5 bombers and place them all in hawaii just because you can!! every turn after that you will probably have 72 dollars, but you must invest in task forces i wouldn’t bother with transports and men until the 4th turn then haul your marines and artilleries and start slaughtering!!
summary- the us could be effective no matter what you buy because they have so much money, but this usually works for me. try to send two task forces. one high and one low. this will box japans navy in, and their backs will be to the wall. oh and make sure you buy a fighter plane for china also, one every round, just for defense. hope this strategy works for you, it does for me, but i cant get into anymore details this post is long ENOUGH!!