As much as I respect Valinn's opinion BurningEGO is right, this is essentially all you need to do. Make sure you have money in the bank at all times. Not exactly rocket science.
Well, in the game I currently have running my retinue is only about 30k. Pikes and cav. When it's all reinforcing, it costs about 100 gold a month. Income without taxing vassals -- with 12 demense, all packed with cities -- is about 70 gold. Unless I save a big cushion, it quickly eats me into the negative.
Now, here's the thing. This is an early-mid game retinue. I ended up expanding much slower than usual due to a few random factors in how the game played out. So, I just took the ERE title and my retinue jumped to about double it's previous size. So, once I build it out, it's going to cost 200gold to reinforce. Which is consistent with other games. My demense income is obviously the same, about 70g.
I just don't see how to make use of a max retinue that costs 3 times monthly income without adding tax. And later 5 or 6 times. Sure, you could save money for wars to use it. But then you're just passing up on building other improvements, fabricating claims, bribing vassals, and all the other things you need to do while playing -- you're otherwise greatly slowing down your game and missing opportunities. You could also not use your retinue. But if you're not going to use it, why have it? Just don't waste money building it if it's just going to sit in the garage all game.
I'd love to be wrong. I really hate the extra vassal relations penalty. But my experience has been that taxing vassals is the only decent move once you become a largish empire. I wait as long as I can to impose tax, but once the retinue costs as much as my monthly income to reinforce I bite the bullet and do it. The choice at that point is to save too much money and miss opportunities, not use the retinue, or go deeply into debt every big war. Tax is the least bad option as I see it.
