Any simple tricks to keep your downloads folder from filling up with junk?

My downloads folder is a total mess right now. it's packed with random pdfs, installer files, and screenshots that i only needed for like two minutes.

I try clearing it out every week but it just builds right back up. don't really want to buy a paid app just to sort out a single folder.

Does anyone use a basic script or automated rule that clears old stuff out in the background?