I have listed my guidelines at Authoring Packages chapter of my book. When it comes to output, there are a couple of things to keep in mind:
main should point to a precompiled version (ES5) of the component you can consume from vanilla Node. This means JSX is transformed to JavaScript calls and so on. This is the absolute minimum you should provide.module should point to a precompiled version that retains ES6 module definitions. Doing this enables tree shaking bundlers, such as webpack, to function. Everything else apart from the module definitions should be compiled. This is an optional step.