...then it's time to get one.

Find a system you like, that will work for you, then stick with it. You don't want to be the person hunting through a zillion e-mails to find the library articles you e-mailed to yourself. You also probably don't want to be scrolling down a looong list of items in your google drive, looking for stuff, either.  Or even a laptop's desktop plastered with document icons.

And please don't be one of those unfortunate people who assumes that every browser's URL will be a permalink...copy and paste them...then discover too late that's not the case, a day or two before the assignment is due...and now you have to go and find ALL the resources again.  Look for 'permalinks' or links meant for sharing...or play it even safer, and just save the item's citation info instead. That will have all the info you need to quickly re-find it; so much better than just a URL.

AND...if you must e-mail an article to yourself, regardless of what you title that e-mail as, PUT A TAG (I recommend in caps as it really stands out) as the first info in the e-mail title: Something like, ENGL ARTICLE or MATH THEOREM  or RAMS101 PAPER, but something....that will stand out when you go to find it or run a search for it in your e-mail. Take those few seconds to give it a searchable title - you won't regret it.  Doing this is especially important if you're e-mailing yourself a PDF that has one of those nonsense numbers/letters titles.

In fact, it's also well worth it to quickly re-name those PDFs you've found that have nonsense titles. Use the whole article title if it isn't too long, or just put the last name of the first author, then the year the article was published.