Living on a superflat world can be a hard task, even for experienced players. This guide will show how to survive and thrive in the superflat enviroment.
Step 1
As soon as you have spawned in the world, immediately look for a village. If you do find a village, run towards it as fast as you can. If you don't find a village, run in any direction until you see one. When you do arrive at a village, check all blacksmith chests for useful items. Although there can be a multitude of items found inside the chest, take everything, as you will find food, armor, tools, iron, gold, obsidian, and diamond all useful. Take some wheat from the wheat fields, and mine some logs from the houses. As soon as you have a few logs, make a single wooden pickaxe and mine some cobblestone and use it to create a stone pickaxe. Collect a stack of cobblestone and use it to create some stone tools (2+ axes, 1+ picks, 3+ shovels and 2+ swords). With these tools, continue to harvest some materials from the village. The materials you should harvest are: wool, wood, ladders, books, pressure plates, cobblestone, iron bars, fences, torches and half blocks. Leave iron golems and villagers alone at this point, as you can probably not defeat them yet.
Step 2
At this point, there are 2 paths you can take. You can chose to continue moving from village to village to amass valuable resources, or you can settle down in one place to farm. The advantage of being nomadic is that you can continue to acquire valuable, non-renewable resources throughout the game, but if you chose to be sedentary, you can have a much easier time building and farming, at the cost of limited rarer resources.
Nomadic
Dismantle the village as much as possible. Take all logs , cobblestone, torches, wool, wheat, and other useful resources. Don't hurt the villagers, however, because if there is an iron golem you will not be able to fight it at this point. Once you have dismantled the village, take shelter in a house for the night, and in the morning take everything with you and repeat the first step: Wander until you find another village. It may be a good idea to keep moving in one direction so that you don't end up at villages you have previously visited. Live like normal nomadic survival, except using resources from the village.
When you have pillaged enough obsidian and diamond from the chests, create an enchantment table. Enchantments are quite easy to get because of the abundance of slimes. Fight zombies whenever you see them to get their iron, and skeletons for arrows. Make a diamond sword if possible, or else an iron one. Your next step is to defeat the iron golem.
Whenever you find a village big enough to house an iron golem, kill it if you can. Because you cannot mine, this will be the most effective way to obtain iron, the other finding it in chests and killing zombies, which only drop it rarely. Dropping gravel on the golem will sometimes kill it, but this is slow and tedious. If you have enough arrows, sniping them can be an effective tactic. Never sword fight a golem without armor, as it deals heavy damage and can kill you in one hit. Whatever method you chose, get enough iron for a full suit of armor and all tools. Enchant everything at least level one, and your armor, sword, and bow higher.
Now you're ready for the next step: the Nether.
Sedentary
If you chose to be sedentary, you focus on renewable resources. Before you acquire them however, begin to make a small house. (You can expand it later.) Or, you can live in a npc house for now, but you Build it a distance from the village to keep it safe from iron golems, and it is advised to have a small doorway so that in the event of a large group of slime getting inside the outer gate, they cannot get inside the actual building. Build an outer dry moat 3 blocks wide to capture slimes and other mobs. Make sure to include a variety of farms in your house (wheat, tree,, cobblestone) as to make the need for a risky venture to a village unneeded. After building shelter, your most important goal should be finding a sapling. They are fairly rare, so you may have to look in several villages to find one. Write down the coordinates of your home and continue out in a direction until you find a village. Take whatever's in its chests, return, and repeat until you have a sapling and at least 3 iron. Plant the saplings, and while you're waiting for them to grow, craft the iron into a bucket. Take water from the well and lava from the smithy to make a cobblestone generator. Now you have a renewable source of wood and cobblestone. Dig a Dirt Mine for dirt, Smelt logs in a furnace to make charcoal for torches, and you'll have everything you need. Your next step is getting renewable iron. Using your wood and cobblestone, expand the village. As it gets bigger, the villagers will reproduce to fill empty houses. Once it reaches a certain size, iron golems will spawn. Make it big enough to spawn several at a time for a more effective trap. At first it may seem like a good idea to just kill them, but this is dangerous and time consuming, so in the long run it is better to make a a trap to kill them. (See Iron Golem Page for more detail.) At this point, it is reccomended to move your house outside of the village or somewhere else safe from rampaging iron golems. Once this is completed, you can sit back for a while until you have enough iron for a full suit of armor and all tools. Before you can move on to the Nether, however, you need ten Obsidian. If you don't have this, go exploring more nearby-or not so nearby-villages for it. A compass can be nice to have in case you ever get lost. If possible, get 4 extra obsidian and at least 2 diamonds so you can make an enchantment table. Surround it with bookshelves from the libraries, and with experience gathered from slimes, it is possible to reach very high level enchantments. Use this to your advantage.
Step 4
By this point you should have a renewable source of blocks, iron and food at your disposal as well as a secure house safe from monsters. At this point you should try and build a variety of non-needed additons to you house. These include: Nether portals, Enchanting chambers(make this before portals), pools and other such rooms. It may however be nessecary to travel to other villages to collect items (diamonds and obsidian) to make such things, and if you do make sure to write down the X and Y co-ords of your house so you don't get lost and having a spawn point set by bed.