I'm a longtime player who micromanages my allies. I like starting in 1933 with hard difficulty and furious aggresiveness. When playing the Axis, I consider taking Gibraltar very important. The problems faced by Great Britain are great enough after France falls. The loss of Gibraltar almost cuts the empire in two. The meeting between Hitler and Franco occurs too late in my timeline, so I try to speed the process up. It takes some time to align Nationalist Spain with Germany. Take control of the Nationalists in the Civil War and reduce the Republicans to one area by the Fall of Poland. The Spanish navy moves inside the Med to a defensible base to act as a fleet-in-being. A small force is left to contain the Republicans and the rest of the army moves adjacent to Gibraltar. Use Diplomacy to move the alignment slider toward Germany. Before France surrenders, have Germany declare war on the Republicans. Usually that puts the Nationalists at war with the Allies. If so, they might be able to capture Gibraltar on their own. If not, the Germans can keep trying to ally with the Nationalists to gain transit rights to attack Gibraltar themselves. The alignment slider moves are costly in money, but are easier than attacking Nationalist Spain. After the Nationalists join the Axis, they finish off the Republicans. With two or three Nationalist divisions on each beach, they can defend their own shores against invasions. Some units can be sent to beaches in Occupied France to release German divisions for the Eastern Front. The low-quality Nationalist bombers are useful sinking ships and convoys in the Atlantic.
As a side note, one of my pet peeves is the failure of the AI to garrison ports that are in paratroop range. This happens even at the higher levels. The airborne lands at night after a huge transport fleet arrives offshore. Even if the opposing AI counterattacks, the paratroops "hold until relieved" by the unloading army arriving at full ORG. I've worked this against the AI to take England in 1939 and re-enter the Continent in 1942. Something, even a militia, should be put in every port by the AI.
I have enjoyed the evolution of this series since the original HoI. I look forward to 1.03.