Step 1: You are going to need quite a bit of tools. Depending on how deep you want to go, you will need a couple of pickaxes, 30 torches, and ladders for how far you want to go down. At your starting point, have a furnace with crafting table and a chest to put your supplies. It wouldn't hurt to have a few pork chops with you to eat. A Stone Pickaxe is the best to use because it is easier to make when mining.

Step 2: Figure out what you want the length and width of the quarry to be. It is best to use 5x5

Step 3: Go to as far as you want to go. Your pickaxe may break along the way but that is okay. Just make a new one.

Step 4: Put ladders on walls to get back up.

Step 5: Go to the level the most ores are found on and make a tunnel. (See the minecraftWiki for help.)

Step 6: Make sure supplies are always put in chests just in cause you fall.

Step 7: Enjoy! You have completed you quarry! There is probably a lot of Cobblestone so use it to make a cool building!!

I hope you found this tutorial helpful. Please leave comments and questions!!