When you’re building on the surface of the world, you need to keep an important factor in mind- enclosure. All the light in the world will do you no good if you’re busily building away or searching for something and a creeper runs into the lit area and blows you up. Enclosure is the first rule of building on the surface, and you need to maintain it for your own safety as well as that of your structure.
No matter what it is you are building, it will always help to put up a fence or a high (two block at least) wall around your construction area. That is not to say that this will be perfect protection (spiders can climb over fences and walls, and Endermen teleport right through them), but it will help to keep your accident rate down.
This means that the first thing you should do when you are building your new home is to create an enclosed room. Windows or not, scaffold or not, you need to have an enclosed space to go hide in if things suddenly go rather pear-shaped.
And, when your structure is done, it needs to be enclosed too- to keep out the monsters and to keep in the animals (if you are herding).
When you’re building your enclosure, there are a few key points to keep in mind.
-Spiders
Spiders, and their far more deadly cousins the Spider Jockeys, are able to climb over walls. Any vertical surface, they can climb on, and that means that a lot of places that are completely safe from most other mobs are wide open as far as they’re concerned. Spiders can climb up the side of any solid surface they like. The best way to avoid having spiders is to have a roof over your head. If you don’t want to do this (for whatever reason) there is still a safe alternative: Spiders cannot climb on the undersides of things. Topping your fences with a set of blocks or slabs will keep spiders from clambering over them. Having a row of stone jutting out from the side of your wall will prevent spiders from getting any higher than that. And making sure that your windows, if they do not have material in them such as glass or a chunk of fence, are not two or more blocks wide will keep the spiders from entering your home that way.
-Endermen
The second greatest threat to a home that would otherwise be secure is Endermen. Now, if you know how to handle yourself around Endermen, they’re actually pretty inoffensive. Still, they can be aggravating- I’ve had a torch on a stone block in the middle of my home where I went to bed to skip through a night and when I got up, an Enderman had swapped the stone block out for a grassy dirt block. Protection against Endermen is pretty simple, though- Endermen stand three blocks high. If a space doesn’t have enough ceiling room then an Enderman might teleport in, but he will also teleport right back out because he will start suffocating. I suppose it would work to have a layer of water on all of your floors or have no floor and build on a lake or something, but that would probably be terribly inconvenient.
-Skeletons
Skeletons aren’t all too dangerous on their own- but they can knock you off of edges into unfortunate falls or worse. Plus, there are always Spider Jockeys. The thing to remember about Skeletons and Spider Jockeys is that any block, even if it has spaces in it (like a fence block) will stop an arrow. Even leaf blocks are impenetrable to arrows. So, use something transparent to make your windows and then you have no worries about being shot at. Also keep in mind that they can and will shoot up or down at you- it’s easy to forget sometimes, and Skeletons have more range than you think. Fortunately, they still walk straight towards you- so pit traps can be fun.
-Line of Sight
Of course, nothing will pay attention to you if it can’t see you. This is probably the biggest reason for having an enclosure- it doesn’t apply to semitransparent blocks like glass, leaves, or fence, but most blocks will keep mobs from seeing you- and that keeps them from attacking you.
-Creepers
Creepers are exceptionally dangerous to player-built structures. This is because Creepers will explode when they are near you. This doesn’t seem so bad until you’re looking at one through a window in your one-block-thick wall and it explodes, taking out not only you but a hefty chunk of your house with you. Make sure that your enclosure includes enough space that you don’t need to stand right next to an outside wall. You’ll be better off for it.
-Aesthetics
It’s certainly possible to construct a building that has only the minimum space for its contents, but there are very few buildings like that that are even a little appealing. Remember, you’re building your home, the place where you’ll likely spend all your time when you’re not out gathering resources and getting yourself eaten or blown up in interesting ways. Make it look nice. Give yourself enough space to move around in, try to avoid claustrophobic little closety buildings. Besides, what will they think? Who is they? Well, it’s....
-Other Players
Minecraft is all well and good, and it’s fun to build things. But for a lot of people there’s no point if you can’t show it to anyone. And what would you rather show someone? A cool idea that’s defensible and functional but as ugly as a seventh finger, or a home that anyone could be proud of, that will inspire them to make changes to their own homes or even entirely new buildings? If you’re playing on a multiplayer server, you will want to have your place look nice- and so will everyone else. Plus, if you’re playing on a server and you get griefed- or even moreso if you’re playing on a server and destroying other peoples’ structures is allowed, or it’s a PvP server or a roleplaying server- you want your home enclosed so that you can move around in it unseen, to respond to incursions. Having a house made of glass may make it pretty, but if someone who wants to steal your stuff knows when you’re home or away, it makes things infinitely easier on them.
Plus, it’s just harder to put a wall of lava up when you can't attach it to something solid.
