Making a small step...
I have had a photograph printed in a book recently, http://www.knowitall.ch/ and that inspired me to create a RedBubble shop, to sell prints/cards/posters of some of my photographs.
http://www.redbubble.com/people/kiriel
It is a fascinating experience to go through my photos with a different eye. Most of my shots have been taken with a view to providing information for other people with similar interests. I take photographs of paintings and then of details such as rings, hairstyles, or shoes. I photograph objects from multiple angles to try and find the details of how the objects were made, to enable others to make similar items in the future.
Consequently 90% of my photos are functional rather than decorative. It seems unlikely to me that anyone is going to pay money to get a card printed of the inside of a coat of plates (although one never knows!).
So I am trawling through my photographs trying to find, well, art. Thinking "would this make a good poster?", "would someone want a card of this?".... I have concluded that I haven't a clue. I will just have to post up photographs I like and discover if there is a market out there. I doubt I will make my fortune with this wee project, but as it costs me naught but a few minutes of my time to post up the shots, I am going for it. Wish me luck!