I know there's tons of modern guides on how to make money, but just in case someone clicks this and not any others.

Get a follower than can level smithing. (they don't already need to be a smith, just be able to level it). After refining some charcoal and iron and whatnot, craft the highest difficulty items you can to get leveled. Give your follower the perk that increases new part discovery for smithing. Once you unlock the Harpoon head for javelins, you have infinite money. I have yet to see a town that could even pay half of what a crafted harpoon is worth. Any city you go to, you can just take all the money in their coffers, and buy anything you want as long as you have 1 wood, 1 coal, and 1 iron to make a harpoon. And in addition, you'll soon be able to make weapons that far exceed anything you can purchase.