Tips to Get Bigger Armies
To get bigger armies than the counts around you do some/all of the following:
- Get a marshal with a high martial score and set him to train troops.
- Improve your holding with buildings that increase your troop count.
- Improve your marshal ability (depending on dlc this can require random luck or even waiting for the next generation).
- Kill their high martial rulers or marshals.
- Save up and hire mercs (and retinues if the applicable dlcs are in play).
- Get allies.
- Get a spouse with a high martial attribute as half of it will be applied (unless they are also your marshal).
- Build (and improve) additional holdings in your county.
If playing as a tribal you can additionally have your steward and chaplain do jobs that will randomly recruit event troops you can use for a single war.
The very early game as a count generally requires some RNG in your favor and/or patience to gain the first county or two and start the snowball rolling.