I am shuddering at some of these responses wtf... :(
I'm a strong believer in Inbox Zero. I have always kept my unread count at zero from the moment I got my first email address and now that I've switched from Gmail to Inbox, I keep my entire inbox count at zero. I archive everything as soon as I've dealt with it and I deal with things as soon as I possibly can so I can get it out of sight and out of mind. Nothing ever gets lost or buried because I'm never overwhelmed by incoming messages and I can tell at a glance if I've gotten anything new to look at. It's wonderful and I recommend this approach to everyone.
I don't organize my email at all once I've dealt with it. At most I have a label set for one or two things, but Inbox itself does a good job of grouping things and Google's inbox search is so good that it's much faster to just search keywords of an email I'm looking for rather than sift through folders like I vaguely remember doing before I got gmail a decade ago.