What Tactics Are Best When Playing the Underdog?

[Chipmunk]

My last two game setups have been 1 squadron of tanks supporting 6 to 9 companies of infantry. I find I always run out of grunts, especially to artillery.

When getting a large infantry force like that do you mount them? When I played WaW I used to buy leg infantry because the front lines were pretty close together but they seem much further apart in MBT and I find if I get leg units it takes them half the game to get to the centre of the map.