Once you have enough levy you can start thinking of Army Recruitment. Depending on the resources available in the settlement they can train to become infantry, scouts, archers or heavy cavalry.
Infantry and the general foot soldiers of the army. The cheapest to recruit, but the least effective unless fielded in large numbers.
The eyes and ears of your army, they can give you an advantage in the battle.
Relatively cheap troops, but still quite effective, they can pack quite a punch if things go well for them.
The most powerful, and the most expensive, they can crush larger armies in one go, but can be cut to pieces if not well supported.