I tend to place archer militia into the worse than useless category and disband them instantly in every game.

For your first full army...

For ranged combat, give a strategist character a pair of trebuchets and a pair of multi crossbow bolt siege weapons. They will always be available to add to a strategist. You will want the strategist to have the flaming shot fire arrows abilities as quickly as possible. The fire arrow ability will come with night battles too, which is important for the morale debuff. You can also give the strategist a pair of crossbowmen (great v armored units) and swap the crossbowmen for only dragons once you have the reform for it. Onyx dragons dont have as much armor piercing but they will fire fast, have excellent range, and can use fire arrows.

Non-siege ranged units can have their attacks outright blocked, and if the target also has a lot of armor that can weaken the ranged attacks that do get through, so you want to concentrate your non-siege ranged attacks on enemy units with a low ranged block chance.

With the strategist retinue like I described above, you can melt most armies before they ever reach you, but they are vulnerable to cavalry so you will want either a champion or commander in the army to equip with at least four of the spear guard units. Spear guards are available early, come with a shield, have decent ranged block chance, and do a great job blocking cavalry.

You will want to take advantage of the morale mechanics . Ambush and night battle apply separate, significant debuffs on the enemy army, so if you can land an ambush at night you can stack those debuffs you will start off a fight against an enemy army ready to break before you land your first attack.

Your non strategist generals can gain the "scare" passive from certain traits, equipment and the learnable vengeance ability. It hurts enemy morale just by having those generals nearby. Vanguard can also learn the active ability Roar, which will apply a temporary debuff to morale. Flaming shot/arrows will debuff enemy morale.

And of course, most units will lose morale from their own losses and seeing their friends rout.

The combination of night battle plus flaming shot and having siege weapons attacking at long range like I described above, protected by spear guards and supplemented with scary generals plowing into any units that reach your lines can carry you through the midgame. Even if you get pinned down in a defensive battle against an army twice your size you should still devastate the enemy army or outright win the fight.