Technology is not going to win the war for Germany. You can change or fine tune their equipment but in the end it will not change a thing. The Allies will adapt to it and, the more effective the new German technology is the quicker the Allies will respond.

There are really two broad items the Germans needed to effectively have a chance of victory in WW 2:

The first is massively improved logistics and engineering. Their rail system needed to be very highly orgainzed to move supplies in a timely fashion where they were needed. It was rare that the Germans made full use of their available rail system. Too often there was alot of slack in line use and alot of wait time for rail cars. Engines were hardly used to capacity either.
In engineering alot more mechanization would have been desirable. For instance, how much difference would it have made for every panzer battalion to have 3 or 4 tanks with bulldozer blades? Rail repair units based on a well equipped train or two would have made a huge difference too.

The second need was for a comprehensive and sound strategic plan right from the start. Instead of a strategic plan that went only as far as the current campaign, Germany should have planned for a strategic war involving all their potential opponets right from the start. This would mean that following Poland, France is planned for and Britain is planned for. With proper planning the Germans could have better tailored their equipment to the war they planned to fight.
Thus, they would not have pushed for say, a Luftwaffe with limited strategic range or capacity. The Navy would have had a more comprehensive plan for dealing with Britain including alot more integration with the Luftwaffe than it had originally. As it was historically, the Luftwaffe on the outbreak of war had no maritime patrol aircraft beyond coastal patrols and air-sea rescue and even these were of minimal number. Once it became apparent that maritime patrol was a mission requirement the Luftwaffe only committed to it on a very lukewarm basis and mostly with pretty marginal aircraft.
Of course, this would have also required that there be no Waffen SS (eg private armies including later Luftwaffe ground units) so the army was a monolithic organization on the ground.