When you start a level, make three or four Air Commands and Barracks or Manufacturing
Facility (just to have some ground units in order to win). Deploy three or four (depending
on how many Air Commands made) Heavy Bombers and after that, some ground units. After the
Bombers reach the enemy's base they will cause a large amount of damage or destroy it. You
may have to queue more Bombers if the enemy has SAM Sites, but it often makes up to three,
so four Bombers would be enough. Note: You must have unlocked Aluminum and Silicon
in order to make Air Units.