The things I rely upon when trying to find subjects for my stock photography are inspiration and creativity. That's why when I've got an idea I write it down, I draw something or...I start working immediately:)
Last week it was around 1 o'clock at night and I was watching tv when it suddenly struck me. So I turned on the computer and started working.Here's the result:


So..my advice is to use every idea you might have because you don't know how well it can work for you and it's also a good way to put that creativity into practice. Stay inspired!