There a lots of great community guides on learning React. Here are a few I recommend:
Build With React
The Beginners Guide to React JS - Kent C Dodds
https://egghead.io/courses/the-beginner-s-guide-to-reactjs
React Lifecycle and Composition - Doug Miller
https://docs.google.com/presentation/d/1ETxmTmxGQfTCc-eCLgUQztwLrb-FIhRLNJ7iacDmrGE/edit#slide=id.p
Of course, a precursor for many of these React subjects is learning ES6. I recommend the following for learning ES6:
You Don't Know JS - Kyle Simpson
https://github.com/getify/You-Dont-Know-JS
A Reintroducion to Javascript - MDN
https://developer.mozilla.org/en-US/docs/Web/JavaScript/A_re-introduction_to_JavaScript
Arrow Functions - MDN
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions
Classes - MDN
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes
Template Literals - MDN
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals
Destructuring Assignment - MDN
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment
The React framework is evolving and will soon give us advanced features to do asynchronous rendering and advanced context APIs. Today, we use the Recomopse library to handle these patterns, but in the future many of these patterns will come out of the box with React.
I recommend gaining a base understanding in these subjects so that you can be prepared.
Learn Recompose and how to write Higher Order Components (HOCs):
https://github.com/acdlite/recompose
https://www.youtube.com/watch?v=zD_judE-bXk
React Context API (not yet stable):
https://reactjs.org/docs/context.html
Once you have learned the basics of React and ES6, I recommend learning some of the advanced React libraries for application state management and routing.
Redux
Official Redux docs:
https://github.com/reactjs/redux
Dan Abramov - Getting Started w/ Redux:
https://egghead.io/courses/getting-started-with-redux
Redux Presentation by Patrick Riley (explains some commonly used Redux middlewares):
https://github.com/priley86/redux-presentation
React Router: React Router is a declarative router for React which aids in simplifying page navigation. The React Router also provides DOM/JSX for further simplifying page routing w/ React UIs.