Summarize the following:
. Find a good cave system until you hit bedrock. This is the lowest you can go in the world, and will help you know how deep you are when you're mining. Diamond ore is typically found in layers 1-15, with the highest concentration around layer 8.  Never, ever dig straight down, as you don't know what is underneath those blocks. You might fall into a dungeon or a pool of lava. Once you hit bedrock, go back up until you're around level 8 and start your mine. Dig a central room about 2 blocks tall, 4 blocks long, and 4 blocks high.  Some players like to start the mine around layer 11. This will result in a slightly smaller chance of finding diamonds, but you are less likely to tunnel directly into a lava pit this way. Remember, diamonds usually spawn near lava. It is recommended that you create a chest in the central room of your mine so that you have a place to store excess ore as you build the mine. Dig a corridor 2 blocks high and at least 50 blocks long in each direction. These will be your starting branches. Walk down one of your corridors and start mining to the left and right every six blocks. This will maximize your efficiency the amount of blocks you can see as you mine. Diamonds are one of the rarest things in the game to find, E, and occur in less than 1% of the blocks in the lower levels. Finding diamonds is more of a game of luck than anything else, and patience is the most important thing to have when mining for them.  If you are lazy and don't want to do this much work, set off some TNT or craft the Wither. But it's best to go into Survival Mode before setting of any explosives. Also, using explosives can shorten your time mining but you might destroy some valuable ores like gold ores or the diamond ores you came for.(The Wither destroys any blocks in its way.)

Summary:
Be a Good Miner in Minecraft Start your mine. Branch out. Keep digging.