I keep negatives in Kenco negative sleeves which are labelled with camera, film and date. These are scanned in and kept on the computer stored in directories/folders named after the camera, sub-directories/sub-folders named after the film and then individual JPG files named after the camera with a sequential number. That makes is fairly easy to locate a given negative when browsing or searching the jpg files.

I do not bother with contact prints as the computer files take on that role.