The most important thing you need is Alchemy building.
This building allows you to get x2 materials of lesser rarity. For example: you can get 200 common stell ingots with 100 uncommon stell ingots.
Go to this building and go to the "Dismantle" tab.
In the photo below, I am doing Dismantle 139 Gold Ingot. After 53 minutes, I should be able to collect 278 Gold Ingots. By doing so, I will be able to sell 2 times more materials. That's almost +1000 Gold in 1 hour.
Gather wood is a very good way to earn more gold.
The secret is that when you go to sleep, you can send your axies to the node where the high level trees are. For 1 night you can get high amount of uncommon/rare/epic wood.
Even 100 epic wood can be sold from 500 gold. And if you are lucky enough to get Mystic, that's about 10-30 gold for 1 wood.
Never leave your land full of trees and stones. Always clean it. And sell everything that remains. You can get more than 3000 gold for selling wood and stones in a day. That's a very good increase for a couple minutes of work.
Always do the expensive stuff. Go to the market and see what's selling for a lot of money.
Usually Platinum Ingot/Ore/Dust. It is better to produce them than Iron Ingot. Either way you need to look at the auction house before making anything.
Try not to sell legendary and mystic items to adventurers. At the market for the same item you can give x3-x10 from the price for which you give adventurers.
Silver/Gold/Platinum Ingots are expensive, but they take a long time to produce. 10 times is 1 hour.
One strategy is to put ingots on overnight production. And in the morning you will have hundreds of ingots to dismantle or sell on the market.