Given I don't play video games to do chores, I don't "farm" (though you might see me doing actual farming/gardening to grow actual food in the real world). I play the game normally and sell things here and there that I don't use, want, or need. Like alchemy ingredients. Because I don't use potions.
Your missed a very common and most profitable way - doing writs on hoard of characters, sell the abundance of materials and items for writ vouchers.
Everything but flipping.