Corruption is a huge drain on resources, and its based on distance to the capital - farther away, a higher percentage of income lost. Any temple, building or road that gives a law bonus offsets it, and can even remove it entirely in some cases.

Temples with Law bonuses are my primary Temple choice in every settlement outside of a short distance from the capital for that reason, over any other Temple choice - for Carthage the temple you will want is Baal-Hammon, which also gives a trade bonus so even better for cash flow. Law also keeps people happier, bigger populations are sustainable, more income. All round Law is great.

Colonies, military garrisons [the building type], roads, walls give law bonuses as well. Some other faction specific buildings like Roman baths give law bonuses too.

Any trait or ancilliary that boosts law helps too and its a good idea to move them to the trade hubs far from your capital. Schools can be worth building because they can generate law boosting traits/followers. The law temples generate law boosters as well I believe.

Other than that moving the capital helps, but for Carthage I think it starts off central to your main trading hub so moving it to help your outlying regions make money might leave you worse off overall in the homelands.

Governor management skill doesnt play a role - it just boosts the settlement income, but that means more lost to corruption as well.