The more you delay construction and improvements, until the very final currently available boss (and even then, with nightly spawns), you will benefit from the increased range of materials and tools available to you, but also take the risk of invasion events bringing more and more powerful enemies.

It's a matter of pacing... The first time you begin to struggle with an invasion, you should sit down and start thinking about defenses, even rudimentary ones. It's not fun to reorganize your food stores and other things just because one greydwarf brute or draugr managed to sneak in.

My favorite building blocks are core wood (especially the 4m beams), stone and tar. The former two are available after the first boss. Stone walls can later be upgraded with other materials. Stakewall will also retain its usefulness due to its durability for cost of materials, and easily adjustable height.

Sharpened stakes may seem appealing and in some cases they can be useful, especially if you don't mind the maintenance, but if they break, you will lose all the material used in their construction.