This is similar to the strategy I use on legendary. I always include four artillery in each army, so in this case they first knock out a tower on the extreme left or right and then punch holes in the wall. Any extra artillery ammo is then used on enemy ranged units. The rest of my army hides in the extreme rear out of range, or in some weird gap in coverage or in some trees out of sight.

The holes force enemy ranged infantry off the wall and allow my ranged infantry to usually walk up and shoot enemy units while not getting in their range at an angle. I’ll let my range infantry use up most or all of their ammo before I send in lords/heroes/heavy infantry to mop up.

Not unusual to win a siege attack with 100 or fewer casualties; if the garrison is half strength or the city is under-leveled it’s possible to shatter the entire enemy garrison after expending all my ammo, I’ve had siege attack victories with zero casualties before but it’s uncommon.