[jms55]

If you want to make nice looking materials and effects, you need a combination of good lighting (comes from the rendering engine, not the material), and artistic capabilities/talent. Art is a lot harder to teach than programming I feel, or at least I don't know how to teach it.

Programming the shaders themselves are pretty simple imo, they're just pure functions that return color data or triangle positions. The syntax might be a little different than you're used to depending on the shader language, but it should be easy enough to pick up in a day.

If you want to write compute shaders for computation, then it gets a lot more tricky and you need to spend some time learning about memory accesses, the underlying hardware, and profiling.