So much of the early Allied strategy is reactionary you can’t sum it up in one post. You’d have to create each scenario and then offer suggestions.
In example, a G1 DOW on Russia would lead to a different UK build than a G2 or G3 DOW on Russia.
A G1 build of Naval indicates a Sea Lion, which is an entirely different build for UK.
A G1 build of all ground units is another entirely different build for the UK.
A J1 DOW is pretty straight forward build for the UK and US. A J2 or J3 is very much different.
Those are just a couple of scenarios. The basics are this: React to the impending threats early. Push your own agenda as the Axis strategy becomes more clear.
The primary keys for the Allies are:
Sink Japan’s Navy by any and all means necessary.
Don’t let London Fall.
Make it costly for a determined Germany to take either London or Moscow.
Shut down Italian expansion before they get too big.
How you do that is up to you.
My friend loves the US 10 Sub purchase in the mid game in the pacific. That usually puts Japan on the defensive.
He also likes to get a Carrier out in the UK the moment the Germans move on Russia, reinforced by 3 scrambling Ftr and 2 Ftr on the CV. He leverages this to either help the US get a TT rotation going into Africa and then later on by defending his TT builds to keep putting units every round on Europe.
He doesn’t believe Japan can win the Pacific as long as he puts SOME US resources there, but he tries not to overspend - his entire goal is to sink Japan’s ships and not spend an IPC more than he has to do it.
He does everything he can to get India and Anzac into the DEI - as that is the Key to stifling Japan’s growth. Taking one DEI for Japan is the equivalent to almost half of the Chinese territories Japan doesn’t start with. It costs less for Japan to get a DEI, so he prefers to keep Japan fighting over the islands instead of reinforcing mainland China.
Anzac is just… slow to play. He generally keeps them far out of the battles outside of taking DNG and flying aircraft to reinforce DEI and/or China.
Russia he plays depending on Germany. I’ve seen him play the counter attack game where he leaves a token force (2-3 Inf) in a territory backed up by a stack of Inf/Art and then he counters the German advances with aircraft and units. I’ve seen him buy Armor/Mech if Sea Lion is obvious. He’s always playing aggressive with Russia or at least passive aggressive. It generally works.
London is touch and go, but generally he doesn’t expect me to REALLY do Sea Lion, so he puts up a token force in London. I took London once while he was playing cat and mouse counter attack in Russia - that created problems for him. I’ve seen him go with 1 Armor in S.Africa and he cleans up Africa of Italian units. He almost ALWAYS lands units on Greece on UK1. I’m not sure why, but he does.
Long story short, you have to react as the Allies early. There is no single blueprint - the closest thing you have is the 6 Inf 1 Ftr on UK1 for London if you scrambled, 10 Inf if you didn’t. The US fleet build in the Pacific is pretty straightforward on US1: CV and BB at a minimum. Everything else, including those purchases are dependent on the Axis moves.