Weapon Heating is one of the most straightforward methods there is. All you’ll really have to do is clear your inventory, buy a bunch of Rosar axes from the marketplace, and start heating them from the "Produce" menu. They will give you a bunch of Melted Iron shards and Trace of Memories. Enough to give you quite a bit of profit, but nothing special.
The real money hides itself in pure zinc shards that have a value of around 100,000 silver. The axes itself cost around 35,000 silver, and the chance of gaining a pure zinc shard is in between 20 to 30%. This means every 3 to 5 axes that you heat, you’ll gain an additional 100,000 silver profit, making this a very underrated and easy method of making silver in Black Desert Online -- especially because it requires little to no time to set it up.