I've got a folder where I put downloads I don't really need in my game at all times - and put them in when I need them again. I also have an external harddrive where a lot of the older downloads went.
an external harddrive or DVD/CD's or something like that is very useful to save the tons of CC you only need once in a while. Also, don't download things if you don't really need them. You don't need the set of 30 pants and 50 tees just because you liked two of them. That's what S2Cleanistaller is for, you know

I once had 10000 unsorted downloads in my l folder. I had no idea what I had, and had lots of downloads I never used at all, especially sims with tons of unneeded CC, and a lot of clothes missing meshes. Now I'm mostly sorting them in folders with pics and links to the exact place I found them - just to know ëxactly what I've got. It's also easier to take out things you've never used, and it's a lot easier to find them if you're looking for a spesific download.