Kill all the cows in the Witcher 3 for easy cash
And they've managed to dig up a pretty tasty exploit - which is a way of taking advantage of the way a game operates to increase your chances of success. In this case, it seems killing and respawning cows is a great way to make a lot of coin, so long as you don't mind sitting around in a field for hours. The exploit goes thusly - find a field with cows in it, murder them all, meditate for a few hours until they respawn then murder them all again. You'll soon have a field full of murdered cow corpses, and the hides are worth 27 Crowns each, that's the in-game currency. Find a shop, trade em in and repeat until your brain can't do it anymore. Here's a video detailing a specific field in the opening White Orchard area which is good for killing.