I have put up a sample repo with the folder structure I currently use even on medium sized projects.
github.com/HerrVoennchen/sample-project
Container Components (usually pages) go into the Pages folder, smaller (and/or "dump") components go into the components folder.
Reducer are summed up in a folder. Actions are in a single file in this example, if they get more then I turn them into a folder alike the reducers.
if you have any questions let me know.
Please note the webpack config is almost unmodified from another project so its kind of over the top for this example.