My America strategy is to throw everything you got against germany, fully before even buying one unit against japan (i’m trying to fiddle around to see what ratio of ipcs i should spend for each front.)
Western Europe can at times be taken in turn one, and if not, men can be thrown into africa. If Britain buys a carrier in turn one and transports, an America buys all infantry and transports, you can slowly castrate germany. Take norway, eastern europe, and with the bulk of your forces aim for Western Europe, outbuild germany, take southern, and then slowly outbuild germany and take germany itself.
Axis and Allies is a race between who can kill the other faster. If the allies can kill germany, and if russia can save itself from japan, the allies won. If Japan builds enough and to take russia before germany is gone.
Personally, every time I see Japan attack pearl harbor, they not only lose their entire fleet (one battleship, one transport, one bobmer, and two fighters if japan didn’t land in hawaii.) If japan doesn’t attack, they could draw the us fleet close to land, and with their giant airforce blow the Americans to smitherines. Just today, i lost a transport, sub, and fighter taking out the entire US fleet. The US fleet has to stay in the pacific to detur japanese forces from total domination of Asia by turn 3. But by turn 4, you have to pray Germany is hurting or the game is over.