From what I've read using Google a good early game stack is 5xINF 1xDragoon 3xART (you can have 6xINF but that may cause a lot of attrition early on)
You want the relationship between INF and ART to be two more INF since they will die.
Later on you can switch the Dragoon to a Hussar, to preserve the recon bonus, early on it may be too hard/expensive to get enough luxury material for these.
Engineers are worse than Artillery I read somewhere for battle, but makes them siege quicker, so there's that.
Tech is important and later in the game with Machineguns the advantage lies with the defender, so even if you have 2x enemy numbers it wont be enough, bait them instead.
Late game just throw 10xARM into a stack and run around.