I started by doing a search using the email address the store emails come from. In this case, I'm creating one for my "daily deals" emails, and am starting with Half Off Depot. My search pulled up a few emails. If nothing pulls up, you may have used the wrong email address or something. If you chose to search by the store name, make sure nothing else pulls up with this search or you might miss other important emails.
Then, I clicked the small down arrow at the right of the search box, which opens a window like this:
I could add more search details if needed, but most store ads shouldn't need any more than the email address. So then I clicked "Create filter with this search" at the bottom right, and got this:
I clicked "Skip the Inbox" (which will keep them from accosting me daily), and "Apply the label" (which will allow me to find them when I want them). I already had a label called "Store Ads", but you can create one - using your name of choice - by selecting "New Label" from that little drop down box. This time, I created a sub label called "Daily Deals". You can choose to check the box at the bottom to automatically apply this filter to emails that are already in your inbox if you want... no real reason I didn't. Obviously, you could also select other options, but for the purposes here, I don't think any are necessary. Then click "Create filter."
The above is my "Store ads" label. You can see that I got 25 emails from 4 stores in 9 days. Hence why I don't want them in my inbox! Since most of the time, the deals/coupons are only good for a week - max - usually every few days or so I click on my "Store ads" label, skim the titles, and delete all of them if I don't need them. But I could also leave them here indefinitely to search when I need something, or clear them out more or less often, as desired. Now that you've created the label, you can repeat as many times as you want to put as many stores in here as your heart desires. Groupon and Living Social are headed to my new "Daily Deals" label as soon as I post this!
Comments? Questions? Throw them at me and I'll do what I can to help.
Managing email-time-tidbits... Soli Deo Gloria.