I think that the most effective way for a ruler to retain order is justice. Justice has many components to it. They mostly fall under Law and Order, but justice is key. We can have numerous laws, but if the are ridiculous, like "Only the First Lady may wear red" then we have a problem. For example, when a parents slaps a child for picking up the cat by its tail or for painting on the walls, that's just. Or for the law of having to pay double after stealing something is reasonable. And besides the law, a ruler must have fitting punishment for those who do not obey the laws. Someone shouldn't be thrown in prisoon because they drove twenty MPH above the speed limit. And the death penalty isn't for those who stole a $1000 pearl necklace. And the leader themselves should be able to understand the justice. What is the point of a king who doesn't realize how to best work with those who have broken the law? Nothing. Jusctice covers it all.