Here's my first advice for you, react.rocks,
this is a web page
that hosts a lot of react projects.
You can also search for certain things there, for keywords like redux for example and then you'll find
some react projects you can check out.
These are all open source,
you can click on them like on this Netflix movie landing page clone and then you'll find a demo link
where you should be able to preview the project
though some of the projects are down but you should always find a code link,
most of the time leading to github, there you can check out this project and that's the cool thing.
You can check out these projects and dive into the code written by other react developers.
Now one important thing, that code doesn't have to be 100% correct or best practice but it should
give you some ideas about how you may optimize your code or how you can solve certain problems
or you simply take one of these projects,
don't look into the code and instead, try to build it on your own and then you compare your solution
to the solution of the original offer.
So definitely dig around on reactrocks.com,
it's a great resource to find some nice projects to learn more about react.