Start with a shovel and a little plot of land, and then dig, sell, and upgrade your way to a very large mining operation. There are a variety of materials to dig through, each with its own sell price. There are also upgrades to help you along your way. You can even hire workers to dig for you when the game isnt open! Dont forget to start a new hole every once in a while to gain experience points and make the digging just a bit easier. Good luck!