It had to be Blitzkreig (Lightning Warfare) in which the tactics were pretty simple - hit hard, fast and unprovoked. This involved bombing polish cities and infrastructure at 4am causing maximum physical damage, destroying military equipment, particularly aircraft, before they could be used and cause maximum panic amongst the population. It wasn't so much a new tactic as carrying the element of surprise to the extreme and not bothering to declare war. A warship on a courtesy visit also opened fire on the Westerplatte without warning. It also helped that, following a pact between Ribbentrop and Molotov, the Germans knew that the Russians would attack from the rear a couple of weeks later. That's a very simplified answer.

I understand that Blitzkreig is a military philosophy of maneuver warfare. Its original intention was to avoid the static battle lines of World War I trench warfare. To achieve this a radical reorganization and doctrine combined tactical air support, armored units, infantry and artillery with a common purpose. This is known as combined arms and is still used to this day.

The intent is to punch through enemy lines and bypass his concentrations. Rapid moving vehicles would make deep penetrations behind enemy lines. This would disrupt lines of communications (supplies) and isolate front line troops from their commands. Like a constrictor snake the coils would begin squeezing the life or ability to fight out of the enemy.