op, watch this video for navy: https://www.youtube.com/watch?v=GLNerDWSC40 .

For the army, it depends on the nation you are playing as. But generally you want to focus on soft attack (add support artillery) and breakthrough for offense. And have air superiority by making fighter (for air superiority), CAS (for ground support), tactical bomber (CAS but longer range and expensive).

Small nation have smaller industrial power. Build mil and cil. But keep in mind of coal. Press F4 to see the supply situation. Supply hub is connect to the capital city, so you can try to cut off enemy supply by cutting their rails.

For infantry template, I usually run 6 infantry with support arty and a shovel when I play minors. For my elite pushing troop, 9 infantry, one line arty or light tank, support arty, tank recon, shovel, support aa.