Even though this is not an official reference guide, it seems to be pretty comprehensive. I am still working my way through it however, I still wanted to list it as a resource.
If you know how to pronounce Na’vi, know some vocabulary, and are ready to start creating sentences, then I think this will be the learning resource for you. Just like above, I am still working my way through it, but I like it so far.
This is pretty much a guide to the Na’vi as a people. It’s completely informational and not for learning the language. However, it’s nice to have all these facts about the Na’vi in one place. I imagine Jake had something similar yet more in depth in the film when he held up that thick textbook titled “The Na’vi”.
A great pronunciation guide with audio clips to get you started! Be sure to click around on the website for some lessons and other resources listed.