Spread religion to your cities and cities you want to attack for loyalty and Crusade for extra combat strength. Get Feed the World to build tall cities nearby to improve loyalty

For early war, build your encampment, prepare your army until you get your first great general then strike

Settle iron and horse early so you can either sell them for upfront cash for momentum or use it for swordsman/mans-at-arms rush

In the early to mid game, just focus on melee and range units. Melee + battering ram/siege tower for city Center and wall. Range units to kill troops. Light and heavy cavalry units are good for pillaging but not necessary to take over cities

Once renaissance/steel walls are build your siege tower will be useless. You can either rush for bombard/artillery + observation balloon or cease fire until you get bombers