Mixins will allow you to apply behaviors to multiple React components.
For ST3 you only need "ReactSnippets.sublime-package", for ST2 you need the entire "snippets" directory.
Aren't mixins effectively deprecated? https://medium.com/@dan_abramov/mixins-are-dead-long-live-higher-order-components-94a0d2f9e750
React.createClass and mixins won't be going anywhere any time soon, but if you want a look at using higher order components in ES6: https://egghead.io/lessons/react-react-mixins-with-es6-components