-When starting level, make three or four Air Commands and on 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 usually makes up to three so four Bombers would be enough. Note: You must have unlocked Aluminum and Silicon in order to make Air Units.
-Build a structure to make money and make everything else to be defense turrets. Make plenty of money and destroy your turrets one at a time. Build barracks and everything else until you have about three buildings. Send out lots of troops to win easily.
This trick only works when you get access to gold. Build four ATGM Sites on the front field. Fill in the remaining space with Economic Committee, and keep raising the tax until you have $90,000. If your ATGM gets damaged repair it immediately. Demolish your structure when you have enough money. Eventually you can get infinite money.