Ok, thanks for the heads up.
I'll get into the American faction, but surely there is a standard early game build that I can use just whilst am becoming accustomed to the new game. (e.g. I know that in CoH, it was standard to go 2 engis -> 4 rifles -> motor pool -> armoured car, then diverge and adapt from there. Surely there is something similar?
As USF it's 4 rifles>Captain tech>Stuart
Grenade tech and ambulance can be rushed by Captain(he can "supervise" unit production and research, making it happen faster) or researched earlier.
Against heavy support weapon play or Ostruppen (a doctrinal Wehr spam unit that can fight only in cover) substitute a rifle squad for a mortar.
Once you get grenade tech, try and use smoke to keep harassing territory and blocking LoS of high damage dealing units. (Like, the OKW Flak cannon is an example of a unit you would block Los of while Rifles cap territory it's protecting.)
If you are playing against a pure infantry spam strat, like 5 Volks or something, substitute Grenades for weapon rack research and start raising the bar.