Your fast-moving mounties tear throughout the map, so leave them in reserve for when the enemy is least anticipating an attack. Constantly keep varied facilities far from hand-to-hand fight scenarios. Make sure you begin a game or two of multiplayer for when you do if you have actually not got time to invest in a huge scrap.
Various Gameplay Tips
Always keep ranged units away from hand-to-hand combat situations.
Your fast-moving cavalry tear across the map, so leave them in reserve for when the enemy is least expecting an attack.
If you've not got time to invest in a big scrap, make sure you start a game or two of multiplayer for when you do.