At the risk of sounding like Mr. Obvious by suggesting you only need to create a folder with a meaningful name and move existing messages to that folder, I share with you Gina Trapani’s take:
I use GMail for my daily messaging and have a slew of folders (or labels, as they’re called here) already set up and actively used. Whenever an email message arrives in my inbox that is not pre-filtered for inclusion in a folder, I manually assign the message to business, council, events, govlist, networks, or something similar. Those act as my versions of what Gina calls reference. Her waiting folder is my “to do” folder, and everything that was in my inbox before watching Gina’s video is now in that folder.
Before I go to sleep every night, everything in the inbox is in one of the folders (if not in the generic GMail archive folder) and I can awake the next morning knowing my inbox has only new items.
There you have it. Create a new folder and move everything from the inbox there. Then, go through the messages; and label or toss what you want. That’s my email method to improve productivity. What’s yours?