How does everyone do it?

For me, I divide the images in to folders that are like boards, so, I have a lounge folder and a hobby folder and so on.
As for how I name the images, they're named by the site I found them on. For example, if I save two images from Wakachan, I name them "Waka1" and "Waka2". If I'm on Horochan, and I save two images that are related to eachother, I might name them something like "Horo1-1" and "Horo1-2".

Currently I just have an img/ directory. I have a 2D/ one too, but it's on an inaccessible drive.

I generally don't bother renaming them.

>>1
I use a combination of by-board and by-topic. My main Pictures folder is divided into "SFW" and "NSFW" folders. Obviously, things like porn and reaction images are by-topic ("Happy", "Angry", "Boobs", "Swimsuits", etc.). Other images are generally by-board if they relate somehow to the board I saved them from (e.g., sad pictures from /r9k/ would go in a folder called "r9k") but many frequently saved into my miscellaneous "SFW" folder.