Here are some tips and little hinters for those who are new to Minecraft. Remember, however, that there are often tips under the 'Trivia' section of an item's page, and are likely to be more in-depth:
Peaceful Mode
Can't seem to figure out those zombies? Too slow for the spiders? Can't make a decent shelter without the worry of a creeper? Low on health and don't have any food? Set the difficulty to peaceful and, voila! Your health will quickly regenerate, your hunger bar won't hurt you, and all hostile mobs will disappear. This becomes very helpful when building large structures or pixel art; however, most players dislike this, as it takes away the challenge and fun of Minecraft.
Tree technique
If you want to get every block on a tree but just can't reach that top one, try leaving the bottom block intact (not cut down) and then jump on it to get the rest. Once done, harvest the bottom. If you still can't reach after using this, you'll have to place a weak block below you to boost yourself up higher... or use an adjacent piece of land and leave more than one block. For 2x2 jungle trees dig a 3 block space and then spiral up, then dig up the spiral from the top, or simply climb up vines, if any (unless you are afraid of taking fall damage and possibly die).
Remember the Pattern
Struggling to remember crafting patterns? Trying to make a bucket but instead you make a minecart (and waste 5 Iron Ingots!)? Take a closer look at a pattern, like the fishing pole pattern. Take notice of how the sticks and string line up to look like a fishing pole. Many patterns follow this trait, such as doors which use two columns of wooden planks to make the rectangular shape of a door, and swords which use two wooden planks, cobblestone, iron ingots, or diamond for the blade and a stick as the handle. Or you could press ESC to stop the game then go to the Crafting page.
Set your spawn
If your house is far from your spawn, and you have 3 Wool and 3 Wooden Planks, you can make a Bed. If you sleep in a bed at night, it will set your spawn, and, like in real life, skip the night. Be careful: if you break your bed, it will no longer set your spawn! Therefore, it may be smart to only move your bed at night, as you can immediately sleep in it.
Shelter Problem
Is it nearing nighttime and you haven't finished your shelter yet? In an emergency situation and need some shelter? Dig three blocks down and place a block above you, and now you're safe! You may want to expand the boundaries so you may place a bed. This method is not recommended though, as you're completely exposed to mobs as you leave. Pillar jumping is another solution. Simply make a pillar directly under you until you are out of reach from the skeleton's arrows. Or you can simply set your difficulty to peaceful mode and relax. (See first paragraph.)
Mining
"Branch Mining"
Make sure you have a lot of pickaxes and at least 64 torches in your inventory. Slowly mine a big stairway to bedrock, lighting your way with the torches as you go. If you plan to have 1x2x2 paths leading off the side of the stairway, bring as many torches as possible. When you get to bedrock go up 12 stairs (to get to the diamond layer) then mine a 1x2x infinite corridor.
Aboveground
Make a 1x2x2 doorway in the back of your home. After that easy step, make a huge room and have several different ways to mine. Low and high, left and right - you're sure to hollow out a mountain soon, getting hefty supplies of coal and iron.
Caving
Find a cave, and explore a branch of the cave. If the cave branches off while exploring your current branch, go down one of the paths at random. When you reach a dead end, go and collect the torches you placed, whilst mining the Coal, Iron, etc. that you passed. After you do that, go down another branch of the cave, and repeat the above process until the cave is done. Now mark the cave in someway so that you know you've mined out this cave, so you don't waste your time coming back.
Mineshaft with a Water Drop
You will need about 2 stacks of ladders, 1 bucket of water, a few iron(or one diamond pickaxe(s)) and a sign. First, dig a hole down to bedrock level. Remember not to dig straight below yourself. If you hit non-flowing lava, stop your mineshaft, or try and find a way around the lava.
Once you do that, place ladders so that you can climb back out of the hole. Now dig a hole adjacent to your ladder hole, so that it becomes a deep 1x2 pit. Go back to the bottom, and place the sign 3 blocks above the bottom. Place your water just above the sign. Now you don't have to use the ladders to go down: instead you can just fall down.
Coal Without Mining
You have made your shelter, already mined some Cobblestone and can't find any Coal to light your environment? Just make a furnace, take some Wooden Planks as fuel and burn some Wood you didn't already craft to Wooden Planks. This will get you some Charcoal which has exactly the same functions of normal Coal that is mined with a pickaxe.
Places to Build
There are some recommendations where a beginner should build and where not: Use any material you want, except Sand or Gravel as they are influenced by gravity (which means that they fall down if no other block is under them) or dirt, because creepers can easily blow it up. Also remember not to build your shelter on Sand or Gravel, because if it comes to your mind to dig down or make a cellar, you'll have a problem because the Sand keeps falling down on you and it will take a long time to remove it from the base.
For beginners, you might want to hollow out the side of a hill or mountain. This can be done quickly and turn into a good shelter, but keep in mind it will be harder to find your home if you wander off, or you could place torches if you have any around the entrance. A second design is to collect a lot of wood and build a wooden house. These stand out easily, look good, and function well. The bad thing is they are flammable (unless you stack wooden slabs).
Darkness
Out of Coal/Charcoal? Remember that hostile mobs require a light level of less than 7 to spawn. Use this knowledge to save some torches in your shelter, though some people say it takes away the fun it very often saves the day if it is your first time playing.
Second-Tier Ores
See some Redstone, Diamond, or some fancy ore? Don't use low-level Pickaxes to mine them, the ore mining as slowly as stone with a hand is a hint that it will not drop anything! Remember, Wood pickaxes only mine Coal and Stone, while Cobblestone mines Iron and Lapis Lazuli. Iron mines all blocks but Obsidian, which only Diamond pickaxes can mine. Be careful - lava lakes often occur at the same level as precious ores.
Item Durability
Mining deep underground and suddenly, inexplicably, your Pickaxe turns into your hand? Is it a bug? Or is it the (formerly) feared Herobrine? It's neither! It's Item Durability...or Uses! Take care to look at the 'health' of your item (the little colored bar underneath the item) before departing on any long trips, be it exploring or mining, as the last thing you want to do is to take the long trip back home just for a Axe, or a Pickaxe. Time is precious, so try bringing along a crafting table, or stock up on tools if you have to.
Ravine Mining
We've all been there. The level generator has created a giant ravine. After you get past the initial "where did that come from?", you'll often see some rare ores within. Well, don't think about jumping down, because that will lead to (almost) certain death! There are two ways that you can to get to the bottom.
One way is to get plenty of sand or gravel. Place blocks in midair and allow them to fall to the bottom of the ravine and stack on top of one another. When they reach ground height, jump on and dig down. (Note: This is the only time when digging down is acceptable.) When you reach the bottom, give yourself a high-five, go get the ore, and re-stack the blocks to get back up.
Another method is to build a simple pool on the edge of the ravine. Leave the side that borders the ravine open. Make a bucket, fill it with water, and fill the pool. The water will leak out of the pool and fall to the bottom of the ravine. This can be used as an easy way to get down and back up. If you're really impatient, you can actually jump down the ravine into the water at the bottom without taking any fall damage. Dont miss.