You know when you find a buyer.
One person may not find your photographs valuable to them but another person might consider your photographs to be very valuable.
I sat on a lot of photographs for a while before I realized that the huge quantity together are valuable to those who need the content depicted in the photographs.
A lot of people wouldn't consider my photogrpahs to be valuable but some do, and it is those people who I'm looking for in order to sell my photographs.
Just two weeks ago I got a call from someone who has been looking for exactly what I have. When he found out about me, I didn't have to do anything to "make the sell", he knew he wanted them.
You probably should determine what the market might be for your photographs. Once you understand that, then you can focus your attention on contacting those people.
What is the subject of most of your photographs? What do you think they can be used for? Why would anybody want to buy them? I'm curious to know myself, but if you can answer those questions for yourself, that will help you to determine who to contact about your photographs.