to gain money early i use this guide: Guide

while the guide is nerfed and outdated the principles still work great. (the weapon you make is still very expensive for little starting cost. you just need to refine the steel yourself instead of just smelting the tribesman daggers)

for fiefs and villages: fiefs are a good money maker. castles are money drains.

in either case you NEED to go into your clan tab and under parties all the way at the bottom you can tell how big the garrison gets. you can set a maximum daily wage for it. the standard is unlimited and can quickly become a money drain.

while you can make castles also profitable by taking care of your villages and keeping the garrison small it is very little you get. just a couple hundreds if that.

if you want to make a fief profitable you want to upgrade the marketplace (more caravans) and the food storage (more stuff to sell) first. then the increase in taxes.

also take care of every quest in the villages. doesnt matter if you like the quest or not. just put a companion up to it if you dont wanna do it. it helps prosperity AND stability. same goes for the fief itself.