It depends, I think economically first. A good army combination is one that utilizes all the resources you have floating (not used for economy or some other purpose). That way, you can make a lot more units and expand faster, which in turn gives you even more resources.
One unit should be very fast and used for scouting, or taking far away territories. With Pan-Asian, I usually make armoured cars and send them ahead. I avoid fighting with them, so they arrive to the back of the enemy country at full hp. Then, I take the country from the back with those ACs.
At the same time, the slower units (infantry from the start, artillery...) conquer the front. Just before daychange, I capture the capital - that way, all low morale provinces I already own get +10% more and don't revolt at daychange. But be careful, the capital bost is instant, so if you capture the capital too early, the provinces gained after it won't get any bonus.
If you go for economy, my suggestion would be 1 barracks lv2 for mot infantry, 1 air factory for interceptors/bombers and 2 ordnance foundries for artillery. The remaining food can be used to sell at the market and buy needed resources.
What would come out, is: 5 mot inf striking at the back of the enemy country, 9 inf + 1 AC backed by 10 arty invading the front. The inf+AC are defensive, so don't drive them into enemies. Stop them before the enemies and let the arty bombard from behind. If the enemy moves, let him drive into your idle stack and don't move it or attack during the battle. That way, your inf will be defending only and will be at an advantage.
