I am an amateur photographer. I joined and then left a camera club as it became clear to me that my photos are not the sort of thing that particular club appreciated. However I am still taking photos and I like them. They tend to be pretty and I think quite commercial nature/landscape photos. Not going to win any prizes but I think they might be quite good for greetings cards, wedding/party invites, calendars. What is the best way to test the waters?
A few sites like Getty images is a place to start. I'm no photographer but used some of their pictures for my website. It wasn't Getty that I ended up using but a cheaper place, I'm sure you could google 'stock pictures'.