If you’re apart of the dark brotherhood, you can do certain jobs that rewards 1000 gold.. or while questing just stash all the loot you can find and sell it
There's many ways using exploits I can think off the top of my head, but the best I've found is learning the transmute skill, buying iron ore off a shop keep, and rolling it over to gold ore and make jewelry
Craft easy to make items like rings, enchant them, and sell them. Higher-level armor will get you more gold. The higher the level, the more it's worth. You'll eventually have so much gold you'll have no use for any of it lol.