I love Gmail because it can keep my inbox clean of everything not important, including most spam.
I use filters a lot. Almost everything is filtered to apply labels.
I use labels a lot. Labels are more powerful than folders, since you can apply multiple labels to a single email rather than just archiving it to a single folder.
When I am on a pc that can handle it, I like the newest interface with the color coded labels.
I can take digital magazine subscriptions and add a label with the name for each magazine, then color code all magazine labels to be same color, then set a filter to automatically label & archive all the magazines when they come in.
When I feel like reading magazines, I can easily find the labels in the list by looking for the color, then reading the label name to see if that's the one I want.
I can take everything that comes from sources related to my money (paypal, bills, bank, etc) and set up a filter to give them a label each, make all the labels bright red so they jump out at me when I see them in my inbox.
I apply a label of "attachments" to anything that comes in with one, which makes it very easy to see all mail with attachments with a single click of the label name.
Any time I see something in my inbox that doesn't have a label added to it, I try to add some sort of label(s) and set up a filter for it, deciding if this would be something I must have in my inbox when it arrives, or if it can be archived for later when I have more time. Anything archived is never marked as read unless the filter is set up to do that, which is almost never. Labels having unread mail appear in bold in the list with the number of unread mail next to it.
I star everything in my inbox that I have read but need to attend to later. (like maybe a reply, or check a link, or make a phone call) I remove the star when the action is completed.
There are things I keep when I am done reading, there are things I trash too. It depends on if it is something that has a purpose in keeping. I have alerts for stuff that serve no purpose after I have read them & responded. They get trashed after I do.
I keep all sent mail, newsletters, anything I might possibly want to refer to at some other point in the future.
I even keep most of that silly crap people forward me, like jokes. I found a "useful" purpose for it and was glad I did, since a friend's mother sent me a few years worth I can use for daily posting on a website. My friend thought it was a real hoot that I started a website from all his mom's forwarded joke emails.
And searching for something in old mail is pretty good in Gmail, so even if I can't remember where I filed it, it's still pretty easy to find.
And I can use a single gmail account as my main account, and make all mail that comes to the rest of my gmail accounts automatically forwarded to the main one and then archived in the original account, label incoming mail with the account name they came from as they arrive. All other filters and labels I have set up will also apply to all of that mail as it comes in. And I can even reply as those email addresses from the main one without having to log out and log into that particular account.
And best of all, since it is webmail, I can access it from any pc (and there is even a mobile version too). It would have been a real bummer when my other pc died to lose access to everything that I had set up, till I had a better pc that could run some particular email client I may have favored on my dead pc, which probably couldn't run on my old slow hunk of junk. And since it is webmail, it's cross-platform too.
(BTW: Gmail mobile & basic html versions have NO ADS