A general word of advice when learning Ember is be very speicfic with dates on the material and version numbers. The API changed rapidly from 1.0 to 2.0 and many concepts no longer apply (e.g. "Views" and "Controllers"). So again, 2.0+ is a must; turn back immediately if it does not specifiy 2.0. Also, do not expect to grasp Ember quickly just because you understand Rails, or React (though knowledge of components and DDAU is useful) or even JavaScript. It requires study like everything else. If you do not already know ES2015, don't worry, you'll learn as you go.
This is an imcomplete list, but I've ordered each category with the things I find the most valuable first.