Hal Leonard Ocarina Method

I think this is a nice book, as are the accompanying videos.

She tries to clarify things in a way that is relatively easy to understand and she has a nice collection of songs one can use. In addition, the practice exercises for familiarizing yourself with various musical motions and for practicing various notes are also quite useful and well thought-out. And the accompanying videos are very nice in the sense that one can use them to actually see the things practically rather than visualizing yourself based on a text description. I would say it is quite a useful resource for people who can't take actual lessons from an instructor.

Finally, it may be a nice way to support the artist. She is quite a helpful and active member of the ocarina community.