Of course, there is a key difficult point in making a treetop home, and that’s getting into the treetops.
The most basic way of getting into the treetops could be considered a ‘wood elevator’, in which you break down the trunk of a tree and then build it back up while standing on it, jumping and looking down to ‘rebuild’ the tree beneath you. While this is the simplest method and a safe one, it has some downpoints. First of all, doing this is very slow, even if you’ve got an axe. And if you’re using an axe, then you run up against the second problem- a lot of excess wear and tear on your tools. And, finally, every time you chop down that trunk, you run the risk of having the leaves of the tree vanish out from the air, causing holes in your floor or walls. Since none of this is desirable, there is a second method.
If you build a ladder on the side of a tree trunk, you have a fast and easy way up into your tree without chancing bits of the leafy structure vanishing. This has its own problems, though. Not least of which is the fact that monsters are able to climb ladders. Standing in the wrong spot can lead zombies and skeletons up into your home if you use this method, and that’s just dangerous. Fortunately, you can place a trapdoor at the top of the ladder to protect your living space, but that still leaves you with amass of monsters trapped in your doorway. It also becomes very easy to accidentally dismantle your own doorway if you find yourself woodchopping (not that hacking down the tree you live in is a terribly brilliant idea to have anyway...).
My personal favorite, though, is to take advantage of the monster AI and use a leaping-gap. What am I talking about? Well, because of the way monster AI is programmed, creatures will not leap on encountering a gap- only an obstacle (or, in the case of spiders, something to attack). Because of this it’s fairly easy to take advantage of a low hill in a forested area- chopping out one or two leaf blocks can leave you with an entrance that takes only a little bit of jumping practice to let you climb up into your tree. This allows you to avoid everything short of Endermen getting up into your tree through your entrance, and also allows you to make the entry to your home open as the rest of it can be.
There are probably other good ways of getting into a treetop home, but they’re likely to be even more complicated- piston-operated platforms, waterfall-switch elevators, and other sorts of advanced redstone contraption. And that kind of defeats one of the major good points of a treetop home- that you can easily begin construction on it right away, with a minimum of resources.
However you set it up and get to it, there is a lot of promise in the construction of a treetop home. It might not be the best choice if you’re angling to get to the Nether and the End as quickly as possible, but if you’re more interested in playing Minecraft over an extended period of time, developing and shaping the entrance to and form of your treetop house can be a very enjoyable activity.