I get about 400-500 non-spam emails a day, and I send about 150. On average, I have about 10 emails in my inbox. Here's how I do it.

Do not ever scan your inbox looking for important emails. This will cause you to scan/read emails more than once, which means that you will be wasting time. It will also allow you to procrastinate the ones you think are non-important, thus cluttering up your inbox.

When you get an email, scan it and immediately do one of the following:

1. Delete it.
2. Reply.
3. Delegate, forwarding it if appropriate, to as few people as possible, ideally to only one person if you are delegating. (If you send it to more than one person, each one will wonder if they are supposed to do something with it or not.) If you do forward something as an FYI to read, please take the time to put in an intro sentence saying why you think this is interesting.
4. Worst case, hold on to it for later action. But try as hard as you can to keep only 10 messages in your inbox! If you ever get more than 10, prune it to do one of the above on each message if possible!

Also, do not create folders. Just use an email client which has blazingly fast search, such as gmail. You will be surprised how fast you can find any email without having to use folders.