This is a list of helpful tools and libraries for React development. It will be continuously updated. Feel free to suggest more in the comments and I'll include them in the main doc as I update.
Materialize-CSS and Material-UI are libraries that have some nice-looking and handy premade components that can be used for React development.
The React Handbook - a massive free guide to building web applications with ReactJS (116 minute read): https://medium.freecodecamp.org/the-react-handbook-b71c27b0a795