To mine correctly first you have to get some wood and craft a wooden pickaxe, then mne some stone, craft a stone pickaxe and a furnace. Then sherch for caves, to find caves turn up your volume and if you hear Ambient sounds then a cave system is close to you, there are also some cave enterences on the surface. In the caves mine for iron then dig down to level 12 (make sure you use a 1 by 2 hole and stand in the middle). When you are at level 12 start strip mining. When you got at least 3 diamonds you can make a pickaxe, go to a cave, and mine some obsidian. THEN YOU CAN MAKE A NEDA PORTA!