Afaik, Hitler deliberately only planned for a land war. He didn't really take a war against Britain in his account. With a little bit more sanity, he'd have known from the time he took office that his expansionist policies might lead to a war against the West, and he'd have allowed his generals and admirals to prepare accordingly.
With Germany not such a big country, winning such wars is only possible with lots of allies, the best available tactics, the most modern equipment, the most effective usage of the available ressources (soldiers, equipment...), and so on.
Germany wasn't able to match the industrial capacity of Britain, even France and Russia were out of German reach at the time afaik, though Germany caught up a lot until wwii started. Germany had some advantages in quality and was good in terms of technology (slightly below Britain, but above France and Russia).
Obvious conclusion is that Germany would need to develop effective and cheap new weapons able to defeat potential enemy tactics, without being regarded as too much of a threat.
They did partly: Their tanks (at the beginning of wwii) were mobile, able to surprise the enemy by crossing terrain not considered suitable for tanks until then, and they were used to deeply penetrate enemy lines to disrupt resupply, military units, and infrastructure far behind the front lines. Their Stukas were also pretty effective at the beginning of the war. Using radios in large numbers was also pretty new for continental Europe. U-boats were pretty effective (despite their high losses), but far too few.
By cutting back on some of the production especially of the very expensive weapons, Germany could easily have had a lot more of their most effective weapons available: More subs, more cannons, earlier and better assault rifles, more night vision sights/goggles, more torpedo boats, and so on.
While from 1933 to 1935, a good defense plan was all that was necessary, as Germany didn't have much offensive capacity then, beginning in 1936, it would have been necessary to make realistic plans for forward "defense" on the territory of any potential enemy - and to equip the military accordingly. That also includes different kinds of landing abilities by sea and air.
Everything together, Germany should be able to launch lots of functioning torpedos by boat and air (the Japanese could do it - Germany should also be able to), to gain sea control in any desired area (not everywhere - just where needed), to land sizable armies on any coast, and so on. Germany should also have spies in every country, able to sabotage transportation and military whenever necessary.
For wwii that means, after winning over France, there is no need to attack Norway. Instead, Germany sinks lots of British ships with subs, torpedo bombers, torpedo boats, mines, and so on. Then, when the British Navy is pretty much unable to counter it, the landings start. Lots of decoys, fake landings, and so on, keep the British busy. The real landings quickly establish a bridgehead somewhere south of London. The air superiority of the British causes Germany lots of problems and losses, but Britain has to surrender after a few weeks or months.