Copywriters have something they call a swipe file — a place they store bits of marketing and writing material they want to refer to later for inspiration. Austin Kleon’s Steal Like An Artist Journal includes its own swipe file.
Commonplace books have a similar idea: it’s a place to store your favourite stuff other people make. H.P. Lovecraft kept one. Ryan Holiday called his “a project for a lifetime.”
You have to make your own wells of inspiration.
For many years, when I saw designs I liked and wanted to save for later reference, I would use Pinterest to save it, or simply take a screenshot and stick a copy of it in my Mac’s hard drive somewhere. (The latter is a much better solution than the former.)
Of course, a screenshot isn’t really enough. A good swipe file tells you where your inspiration comes from. It should include notes. Maybe even a full taxonomy. At that point, your basic file browser ain’t going to cut it. There’s no way to serendipitously discover things in the Finder.
These days, I like using Eagle, a macOS app that does a great job organizing all the visual media it saves. With support for everything from pictures to videos to full webpages, I think the app is a godsend. I was suspicious of it at first, mostly because it seemed to good be true, but it has survived three computers and a silicon transition without losing a single image, so I’m pretty confident in it these days.
It’s unfortunately Mac only, but it’s a darn good Mac app (if you like Mac-assed Mac apps). If you’re a Windows person or love your iPad for this sort of thing, I can’t help you. But I’d love to hear what you use.