USE CLOSE PROTECTION:
Get a scout and a jeep, then move forwards onto a new map. Then keep on getting jeeps (if someone dies get a jeep person). After you have more than 7, send jeeps to a new map in 4 or 5. I got so far in this it is not funny. You won’t need anything else because every time you move onto a new map the game basically resets and starts sending out infantry. Don’t spend too much time (3 waves at most) on each screen.
Some of the tanks just don't lose health! I bombard it with a T35 for more than 2 minutes and the health remains the same! I think it may be a glitch or something!