I have recently switched to Bulgarians because I like the cheap blacksmith upgrades and the free infantry upgrades.
With this said I build 2-3 barracks while aging to fuedal, create 25 infantry ASAP. (25%spears/75%man at arms, Do not stop making Villagers) Then send them as a raid/scout to your enemy.
If they are walled up or have too many arrows, bring your military back home, boom to castle and add 1-2 more TC’s.
If I am in Age castle+ I keep a main force of infantry with rams and a support of cavalry, keep the CAV hidden in the fog until you have a favorable battle (I mix my unique units with hussar and knights) My infantry are very expendable and have my barracks always qued with more units but I do my best to keep my CAV moving, even letting their military pursue to get them out of postion.
I think the earlier you put pressure on your opponent, the better.
In my team battles and late game I have noticed my units arent as strong.
The free and cheap blacksmith upgrades mean your infantry units should be superior in early Feudal or Early Castle.