True about the texturing aspect, unless you become a procedural material genius, but even procedurals have their limitations. It's no accident that people use good old fashioned image maps for textures, and although they can be created with photographs, still, a decent drawing technnique would be a prerequisite. But one of the best things yu can do for yourself in 3D is to just look around at simple everyday things. Look at shadows and highlights. Pay attention to how far away something that's twice the size of something else has to be before it appears to be the same size, according to your Point Of View (POV). In all of art, there is no better exercise than simply paying attention and learning how to "see". If you know how to see, then you've got half of it right there. And anything and everything else trechnical you learn how to do will always depend upon that ability to see.