Sheraan Amod from Personera??showed me a cool trick at Geek Retreat??on how he keeps his Gmail inbox entirely empty.
First, enable Labs (if you haven't already) and then enable Superstars:??
Sheraan uses his stars in the following way:??
Red Bang: Requires urgent action response from me
Yellow Bang: Requires urgent response from someone else (tip: click "view message" after sending something important to cue yourself to check up on it)
Green Tick: Waiting on external response, not urgent
Yellow Star: Not urgent, action required should I choose so. (For example: email from bank to update account details, random question from a stranger, email elaborating on an idea I want to expand on later, etc)
Blue "i": Reference material or extra info to read.
Go through your new mails quickly, star them accordingly and archive them all so that they're no longer in your inbox (Make sure to use Gmail shortcuts: j for next, k for previous, s for star, y to archive)
Then review the starred mails daily??in order of priority (Search for "has:red-bang" to see all your highest priority items)
In addition to Sheraan's method, I also use Multiple Inboxes, so that I can always see the urgent emails at the top in a panel above my main Inbox. (I use has:red-bang has:yellow-star at the moment)
I still find filtering >150 emails a day tedious, but an organised approach helps a lot.