For the tiers themselves, I want to keep a ratio of roughly 13:4:2:1, namely for every 13 Hired Soldiers (recruits promote so quickly I won't count them) that I'll want 4 of the next tier, and for every 4 of those, I'll want 2 of the Cavalry/Veteran Warriors, and obviously for every 2 of those, I'll have 1 Hired Knight/Hired Foot Knight. I know Cavalry is great, but the Infantry blobs can just overwhelm cavalry save for Eagle Knights, Dreaded One spawns, etc.
For every 2 Infantry, I'll have one Cavalry. So, I'm really getting into Perisno, and I've pretty much fallen in love with the Hired Mercenary Troops because I can adjust their equipment to match my needs (blunt weapons for prisoners, Piercing for Sieges with heavy armored enemies, slashing for lightly armored sieges) and before getting off the ground with multiple enterprises and Fiefs, I'm considering a 2:1 ratio for Infantry and Cavalry.