I just started with a new account on 123RF.com (123RF.com) and uploaded some of my photos there.
I just started with a new account on Gettyimages (iStock) and uploaded some of my photos there.
I have put some of my work on werkaandemuur.nl (artheroes.com) for direct ordering of prints.
As I have a lot of editorial pictures I also joined the Alamy stock agency to see if customers there would be interested in my work.
I also opened an Adobe Stock account to publish some of my commercial (non-editoral) photos.
I have recently become a contributor at Shutterstock and have added some of my images on the Shutterstock website. Although creating stock photos is not the goal of my work, I do find it interesting to see if people are interested in my work for commercial or editorial purposes. See shutterstock.
I finally started my own photo site. After publishing many of my photos using sites like Flickr, I finally decided to create my own website to show some of my best photos. As I am seriously considering to make a living of photography, I thought it would be better to have an own site where I can show my work and which I can use to get in contact with people who would be interested in my work or who are also passionate about photography and who like to get in contact with me.