The Luftwaffe was established in 1933. Six years later it was the best operational air force in the world. How on earth did this happen? Read this book to find out.
First of all, it had the typical German advantages: World-class aeronautical engineering. Sound practical military thought. Thorough joint training and exercise. Well-organized logistics and support that allowed operations from airfields close to the front, allowing pilots to fly 3-4 sorties per day.
Then there was carefully evaluated operational experience in the Spanish Civil War.
And the German airmen were not mesmerized by the vision of strategic bombing quickly winning a war all by itself, as the USAAF and the RAF were. The Germans recognized the value of strategic bombing, and even viewed it at the primary mission of the Luftwaffe, but they also recognized the importance of cooperating with the army in a joint campaign. It's true that the Luftwaffe never deployed an effective heavy bomber, but it wasn't for lack of trying; they were just a few years behind the US and the UK in the high-power engines necessary, and their development took a wrong turn to focus on dive bombing after that proved so effective in Spain. Anyway, their primary possible adversaries (France, Poland, Czechoslovakia) were well within medium bomber range.
By the way, the horrifying terror bombing of Guernica, made infamous by Picasso, was no such thing. Guernica was a small town of 5000 not far behind the front lines. It was bombed because it was thought to be a center for reinforcing the front. All the rest was Spanish Republican propaganda.