Severe,
For learning to control your units on the battle map, I would recommend the following strategy
First, learn the stats of the major line units of each civ. You'll know them all eventually, but knowing the line units stats is more important early on than knowing the stats of special units (mercs, arcani, etc.)
Second, fight a series of battles on the quick battles map, setting a medium amount of denarii, a fairly open field situation (no bridges, sieges) and you using an infantry based civ (no parthians or scythians yet, they fight a different kind of war), I'd recommend a greco-roman civ like any of the factions or Greece, or Macedon. Give your enemy another infantry civ, say Gaul or Dacia, or Spain. Hold off fighting the elephant or cavalry civs until you've mastered micromanagement.
In these battles pause often to review the situationand make moves in the first ones. Learn how to control the troops with hotkeys, and learn to rough estimate missile ranges. As the series wears on, increase the amount of time you go between pauses until you cease pausing all together. The key here is to pause and see the full situation of the battle, but as you gain experience the minimap and a quick overview is all you're really going to need. Develop a battle doctrine, and improve it until it becomes a regular source of victory. Fight battles against varied computers with harder difficulties and with you using weaker armies.
Practice Siege and Countersiege warfare. Not with the dream teams such as 20 urban cohorts, but with armies that you will likely field during a campaign. The key here is to develop sound doctrines of siege, because when a battle gets going, the poop will hit the fan. Learn which combinations of siege engines work, and in what situations.
Finally, go online and play multiplayer. You will, unless you happen to be Field Marshal Erwin Rommel, loose an ungodly amount of early battles, but don't loose heart. Eventually the Win/loss will even out and you will be well on your way to being a master of ancient warfare.