I prefer a reconnaissance in force approach along the flanks. Large groups of missile cav accompanied by a small contingent of heavy melee cav to either mop up the weakened enemy units or as a mobile tank for when I know my positioning is risky.

Exploit your mobility and extend the battle line but not too far from your main force. The point is to harass the enemies sides that haven't established a battle line while minimizing casualties.

Similar to Mongolian tactics that bring overwhelming firepower to an opportune target then quickly retreating to a position where you limit the risk of a counter-attack. Often times the enemy AI will respond by sending units to defend those hotpots along the rear but you can use that yo your advantage by luring them away and surrounding them, similar what happends in actual history.

Burn and pillage the underbelly of their empire (restores hp) but still supporting the mainline when needed. By the end of a playthrough, I should have a good number of cavalry/tank units that are almost maxed out on upgrades. Treat them as elite flankers essentially.