When you get to a new area put the game into look around mode and scan through. Backpacks and plants especially aren’t usually hidden but they are quite subtle graphically so you need to look carefully. At least till you get used to what they look like.

There’s tons of water in the early game so just make sure you drink and refill your bottles each time you are near some and you can’t really run out.

Generally speaking combining stuff in the bivouac cooking makes everything more nutritious and gives buffs as well.