I often get comments on my sense of lighting and color, and my use of detail. Today a little about detail. Observation. That’s the first bit. Really looking at something to the extent that you can see its parts within the whole and imagine how you can make the right marks to produce an imitation. If you haven’t found or crafted the tools (practical or digital) to make the marks you are in need of, attend to that. Practice making various textures and surfaces with attention to light direction and intensity. When you gain mastery of a particular texture such as fur, tree bark, polished steel, etc. you can then apply it to regions of an image where it will serve well. After that it is about having the patience to complete the thousands of gestures required to make it emerge. Go do it.