Army upkeep costs can be kept down by using peasants or town watch instead of hastati or cohorts. Definitely not worth paying upper-tier soldiers to do a job (sit down in city) peasants can do just as well.

Ports and port upgrades are big piles of money, though as the Brutii you should have conquered Athens, Sparta, etc. which are the most profitable places. If you are in Egypt make sure you capture the Great Pyramid for loyalty's sake.

Raising happiness and health in a settlement lets you raise taxes while keeping the face blue or above. (Temples, Sewers, Roman Coliseums) Temples of Juno should be built at the fringes of the empire, not Mars which should be in the huge cities at the center.

Think about relocating the capital to a central part of the empire if distance to capital is causing too much unrest (and preventing the taxgrab).

High management family members can increase productivity in a settlement, high influence governors keep public order high.

And AutoManage totally sucks. Do it yourself. If all else fails, go west to exterminate carthage, raze the buildings and abandon it.