I use a Crossfire tactic personally (thats what i call it).

heres some images of it...
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here, the selected unit is firing at the farthest one, while the farthest one fires at the closer one that we can see is routing.

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This is basically how i set them up, with a wedge formation and with a gap in the center (this ones a little stretched out actually, i usually have em almost shoulder to shoulder on the ends).

When the enemy engage to melee, your naffatun have a clear shot at the units on the opposite side. This strategy actually works quite well with archers too, since your archers have a clear LoS and can pelter the enemies on the opposite side in either their sides or backs. The biggest factor in this, is having troops that hold the line well, or don't get completely decimated by a cav charge (spearmen is what i use, even against DFK's, and other armoured hvy infantry, since they hold better against a cav charge).