The Luftwaffe was unable to keep up with all the demands of the various fronts. It was forced to spread itself thin and things worsened because of a supply nightmare.
It also functioned basically as an aerial artillery for the ground forces. If it was able to evolve a better doctrine, the Luftwaffe could've been more effective. For the short term, I'd say the Germans needed an effective fighter that had an extended loitering capability (very useful over England during the Battle of Britain) and a deep penetration long range bomber (useful in at least hampering the production sites of the USSR), plus a proper doctrine for its use. Of course, a better commander than Goering would be needed.