Do you like fishing? When I first started tinkering, it was a lot like sitting in a boat fishing. I started with a handful of images related to a niche and a spreadsheet. I posted them to a few social media sites just to see what would happen, and I wrote it all down. Waited until a different day at a different hour, posted more, took notes. Changed some colors on poor performers and tried again, took notes. After a while, I kinda knew what photos worked on different sites. I know it's not SEO per se, but that iterative process really allows the abstract "what is good and what isn't" that no one can really answer to work itself out. With SEO, it's all about the data as well. You can read up on it until you're blue in the face, but until you can see with your own eyes how your own actions change the results over time, you'll never be able to apply it. With me, I had to change my perception. I wasn't building sites or social accounts, I was building experiments and in that frame of mind it became much much clearer.
