Gold income

There are 2 ways to increase gold income

The first is adjusting your taxes.

The second is doing advance builds like increasing the levels of your common ground, mage tower, consulate, blacksmith, fletcher, spearmaker, tannery and forge or advance basic resource builds which are you kiln, stonemason, foundry and carpentry. ALL will increase gold BUT it will also effect your food so you will have to watchout for that, increasing the level of your farmyards will help.

Getting a balance between your food and your gold income is important since both are BIG factors in the functioning of your city.

NO food means unable to produce advanced resources like livestock, horses and beer and need all 3 to make specific troops and diplomats.... no livestock means no saddles or leather armour and no horses means no Calvary troops.  Some diplomats require saddles, beer and horses too.

NO money means you will be unable to support any troops or diplomats. The troops and diplomats you have made within a city that has run out of money will ALL disappear cos you can no longer pay them. This could be disasterous for you as it will mean your city is defenseless until you can get gold running positive again into your city