I played my first few games today. My results were varied between coming first or second in a match to coming close to last. Generally, I found infantry to be fun to use, although it was very frustrating if the enemy had a decent support player, whereupon my infantry can't move fast enough to both capture points and evade artillery. I'd usually try to tacstrike the enemy's artillery, then.
With armour, I have no idea how to play armour. I had some success using a combo of 1 midAA and 3 heavy tanks, although those ended up being tacstrike fodder. A comment on the tankspam comment above. I had some fun driving eight light tanks behind enemy lines. They only killed three heavy artillery, but it was joy.
Air, I seem to be the worst at. No idea why.
Support was fairly fun, especially if there were a large number of aircraft players on the map.

I couldn't find out how to have large numbers of heavy artillery without totally ignoring everything else (e.g. heavy AA/repair vehicles).
I was also the only person I ever saw to destroy a bridge.
>>Your head hurts.
>>Quaff painkillers
>>Your head no longer hurts.