You'll find abandoned structures around the world. Pro tip: In the Meadows, you can occasionally find beehives in them as well. Craft a bow and shoot them down, or use a spear and throw it (mouse 3) to break the hive and obtain a queen bee, which is used to make your own beehives to make honey.

After you find your first few branches you can use that to make an axe. Then you can just chop down trees to get the wood you need for everything else.

Building near water is ideal. Eventually you'll need to make a boat and head out into the ocean to search for other islands. There are also Neck along the shore that you can hunt for their tails as a source of food, and flint used to make your first upgraded weapons and tools.

There is no hunger or thirst in this game, but food plays an important role. Food increases your health and stamina temporarily, which helps you in various ways. Meats tend to provide larger health bonuses, while fruits/veggies provide larger stamina bonuses.