Like I mentioned before, practicing these in Creative will make it much easier for you, and feel free to research other ones or tweak them however you like.
Building in Fortnite has evolved tremendously since the game came out. Building techniques have been around for a long time now and have been refined, so learning a couple of them will make the difference. There are many to learn and each one has a different difficulty associated with it. I will go over three, ranging from basic, intermediate, and advanced. Like I mentioned before, practicing these in Creative will make it much easier for you, and feel free to research other ones or tweak them however you like.