Yeah that tutorial is decent its what I used to get going.
Note that all of the images in those comfy tutorials (except for images of the UI itself) can be dragndropped into ComfyUI and you'll get the entire node layout you can use to understand how it works.
Another good resource is civit.ai and specifically look for images that have a comfy UI embedded metadata. I made a feature request that they create a tag for uploaders to flag comfyUI pngs but not sure if they've added that yet. Or caroose Reddit or Discord for people sharing PNGs with comfy embeds.
Trying out different models (also avail from civit) is a good way to get an understanding of how swapping out models affects performance and the results. I've been abusing Absolutereality (v1.81) + More Details LORA because its just so damn fast and the results are great for almost any requirement I throw at it. AI moves so fast but I don't even bother updating the models anymore there is just so much potential in the models we already have; more pay off would be mastering other techniques like the depth map Control Net.
I would say that above all extensive familiarity with an image editor like Photoshop, Gimp, or Krita - will get you the most mileage particularly if you have specific needs beyond just fun and concepting. AI art makes artists better, people who struggle with image editing will struggle to maximize this new tech just as people who struggle with code will have issues maintaining the code Copilot or ChatGPT is spitting out (versus a coder who will refactor and fine tune before integrating to the rest of their application).