In addition, do the Westwall national focus so you can have fewer troops on the French border allowing you to focus on the Belgian invasion.
With regards to your navy, it is worth doing two separate fleets: a battle fleet with battleships and destroyers in and a sub fleet. By following these rules below, the chances of securing the fruits of war will dramatically increase and your journey towards global domination will be one step closer.
As with our Soviet Union guide, I will provide some general rules that you should follow even if you decide not to adopt my military tactics.