While as the GDI and your enemy likes air units or missiles, surround your base with the Firestorm Wall at a distance from your base, backed up with RPG Launchers. Whenever aircraft or missiles are detected coming toward you, turn the Firestorm on. When aircraft attack, wait until just before they cross the Firestorm line so that they cannot turn away before they are hit. Don't worry if the Firestorm is attacked by the enemy aircraft -- it is pretty tough. Simply bring some MRLS in to assist destroying the aircraft.