back in the days of film I was member of both ASMP and NPPA and had two agents that dealt with stock photos and assignments, Agency France Press and silver image, never made too much money off stock photos, paydays are from assignments and things like events usually an assignment say for example gymnastics national championships, you get paid for travel, time, and then get a space rate based on what is published and where. or an editor will negotiate a flat rate for a job but you'll get your images sent back to agency to be kept on file for stock requests. or just going to events and shopping around for buyers, for example I remember one year going to Daytona Bike week and cashing in big time selling covers and a couple double trucks to easy rider and Lady Biker Magazines, big magazines like National Geographic, Newsweek, business week, time and the like also pay well. Ive had pictures published all over the world and won a bunch of awards, but I'm still a near nobody in the world of photography. There are a million people who want the one job. Of course today nearly everybody in the world has a camera with them at all times. there are billions of pictures on the internet. If your pictures stand out and have great or unique subject matter someone might have a use for them and you might be able to make some money from them if you deal with a trustworthy agent. Still today some of the top magazine photographers in the world still use fujichrome from what I understand.
good luck to any of you who want to put you pictures up for stock