When it comes to art process, I usually start with a small thumbnail while also trying to not care too much about details at first. From my experiences training myself with doing storyboards while also doing movie studies (SHOTDECK and FILMGRAB) does help myself a lot when it comes to composition. This video is pretty much a summary of my process when it comes to thumbnail. (rule of third and golden ring does help as well when making compostion)

If you want to go on a more "surreal" composition I definitely recommend to check graphic design on pinterest (I don't really like the website due to stolen art and gen AI unfortunately it's also good for inspiration). Mixing illustration with that can make some interesting results

Since coloring and composition often goes hand in hand. I highly recommended checking Johannes Itten's 7 color contrast

Because it does talk about color theory while also helping you with composition as well