There are many ways to get past each zone, these are the ones I used.

Zone 1 - Checkpoint
Destroy the guard tower, brings air strike, makes it easier.

Zone 2 - Town
Stay close to transport, riflemen or anti-infantry tanks, or engineers/flame.

Zoner 3 - Sniper Bridge
Tank to take sniper fire. Use morters to take out snipers as your rebuild bridge.

Zone 4 - Fishing Camp
Finish paratroopers around transport. Defend base. Then rebuild bridges. If you rebuild briges first it will be very hard to recover from.

Zone 5 - Docks
Transport is safe in hanger, try to take out troop trucks before they unload troops.

Zone 6 - South Docks
Have AT ready for tank attack

Zone 6b - Boat launchers in nortt dock. Have anti-troop MG/morters/tanks ready. Watch two stuarts that come from south dock hanger. Watch for 3 snipers on bridge will destroy transport. Must capture all points to continue under bridge.

Zone 7 - Swamps, take out those two guard towers, they are calling in the artillary. use tank rush or air strikes fast.

Zone 8 - Take out base guard towers and AT positions.

Zone 9 - Destroy all eight barracks to stop troops from attacking. Make sure transport is healed before final drive home.

Only thing that heals transport is vehicle bunker repair. use it wisely.