I would recommend the books Ostkrieg, Why the Allies Won, Russia's War: Blood Against the Snow, and Clash of Titans, also A War to Be Won. The Germans' failings in this war on the purely military level are too many to count, the most obvious being that they consolidated literally everything it was possible to do so and man that weren't in the hands of one man, while eschewing deliberately any kind of strategic joint planning in the sense of the Soviet Stavka Glavnogo Komandovania or the WAllies' Joint Chiefs of Staff.
This was compounded by the Nazis creating no less than three separate field armies in the course of the war: the Wehrmacht, the Waffen-SS, and the Luftwaffe. The problem is that with a much smaller pool of resources the Nazis would have done better to create a larger Wehrmacht and forget the concept of an SS parody of the Heer and *especially* giving the Luftwaffe its own separate forces. By the end of the war, as a result, the LW was weaksauce, the Wehrmacht was akin to the regular Iraqi Army, and the Waffen-SS to the Republican Guard.
Next, the Nazis won their short wars by lurching from one opportunistic moment to the next, their only overall plan was a vague concept of war with the Soviet Union, preferably together with the British Empire. This is fairly workable so long as the enemies chosen are the variety that will fall in a maximum of six weeks. Against say, the Soviet Union or the United States it's a recipe for clusterfuck and that's just what happened with the Nazis. Their only saving grace earlier on was in fighting people more incompetent than they were, or too weak/lacking modern equipment to do anything to them to start with.
After this you've got the vast differences between the victorious Allies and what the Nazis did, the differences that enabled the Allies to translate their successes into failures. First, the very brutality and savagery of the Nazis guaranteed that an intact Nazi state would see the unlikely coalition hold together because everyone understood what a treacherous lout Hitler was.
Second, the democracies and Soviets both developed large, firepower-dependent forces that sought to wage a mobile war. The Soviets, who destroyed Sixth Army (twice), destroyed Army Groups Center, South, Vistula, and won a sequence of grinding battles that produced large-scale victories over Army Groups North and South, as well as against the Courland Pocket and elsewhere in the war did a better job of the ground fighting than the democracies did, but due to this the democracies had more ability to recover from their own errors than they might otherwise have had, while Nazi losses in Italy and in the West were much less replaceable due to the East being the real war.
Third, due to the Nazis gathering against them this huge coalition the way the United Nations worked together actually formed an alliance where the whole was greater than the sum of the parts. The Nazis record of betrayal and brutality to all their allies ensured that in the end Hitler got his wish of Germany v. the world, but reality did to his wishes what it did to so many other thugs' fond dreams.
