There has been a lot written about this subject, but it's worth taking a fresh look. In the past, many suggestions for structuring your email folder hierarchy was influenced by the available technology and limitations thereof.
My recommendation for structuring your Inbox is to keep it as simple as possible. You only really need 3 folders:
This folder exists by default. Your Inbox is for all new mail.
Any mail that has been dealt with, should simply be put into one large archive folder. It's dealt with and the chance of you needing any of these emails in the future is very low.
The waiting folder is for any email that you will need to come back to in the near future. This is usually when you're waiting for a response or resolution on an issue. Once that happens, all emails related to that subject should be moved from the waiting folder to the archive folder.
Many things have changed in recent years, so your Folder structure can reflect this now. It takes a lot of time to continually be filing emails into individual folders, and the chance of you needing to refer back to one of those emails is pretty low. With modern search tools in both webmail interfaces and email clients, you can find any email in your archive folder much quicker than the sum of the time it would take to keep filing email into separate folders.
Of course you can create other folders if you need them, but ask yourself if you really need those folders. The simpler you can keep things, the better in the long-run.