Macemen are very cheap shock infantry and can quickly remove a few units for just a mace and 10 gold. Generally a tower filled with crossbowmen stops most aggression, under the guard of bulky melee troops. That said, don't go mass mines or quarries just for bulk sell. You can also sometimes get into a situation where the population won't fill up completely, use these opportunities to get a tax one level higher (mostly occurs with 13 peasants and 16 cap in the beginning of the game). In SHC2 most of your gold comes from taxation, as resources generally sell insanely low. You should branch into ale or candles to amp popularity other food types are not really worth it because of their comparatively reduced output rate. In low resource games, initially it is best to build mass woodcutters to establish a bread economy and recruit fodder units (conscripts, slaves) while you get a weapon production up. It can extract way more gold than you in the beginning of the game, so your best chance is to turtle until you can steamroll it. On top of other answers, you should know that the AI cheats heavily to build itself up (I think mostly to give the weakest characters a chance).

Stronghold crusader 2 gold cheat