I save a lot of images, whether from 4chan or otherwise.
Right now, I use hydrus, a media manager that's like a local booru: order by tags, automatically download from boorus once a certain tag has new images added, powerful search...
I just do a one-click download into my import folder on Firefox then either let it tag itself if it's an Anime pic or add tags manually otherwise (most common either being board tags or a "reaction" tag).
In total, I have about 55k images, most of it being Anime pics. I've started giving ratings (based on a 3-star system for good, great, or excellent) to most of my artwork, being at around ~3k rated images right now. Progressing slowly, but at least it doesn't get worse since I rate all new images.
I'm planning to delete all of my unrated pics once I finish so my archive looks at least somewhat curated.