They can be tricky, but 2 things help here: scale, and material. Wood is flexible and has some play, so you can wiggle things into place. If you go too small, you have much less play and it gets more difficult, especially at the end when the rest of the model is reinforcing the position of the parts. For a very small taste of this process and method, check out my octahedron post, they use essentially the same construction method, just on a much smaller scale:
That one goes together in just a few minutes, piece of cake.