For the model itself, the body is quite easy because he doesn't have any legs and just a flat base to his robes. The head is more detailed though, especially around the mouth and eyes, so make sure you score the lines to get a neat shape. At many points in the construction you can use holes in the model to secure tabs from the inside, but finally closing the whole thing might be a bit tricky depending on what order you make it in.
Scaled to my other characters as usual, and stands about 17.7cm tall. Sounds small but remember he is very hunched over and actually has a large head.
The paper model is from http://hyrulepapercraft.blogspot.com