The pants were a good exercise in shadow and highlight placement. It's all based on zenithal lighting or what's called the stop sign rule (image below). Imagine a light above the figure and light/dark is determined by the angle of each surface.
There are a lot of small folds so you've got the highlights on the upper surfaces. As we go around to the insides of the legs the light gets blocked so even the upper surfaces get pretty dark (it's a tweak to the stop sign rule, but true to the basic idea - how much light would hit the surface). Then there are the larger surfaces. His right leg which is mostly straight so I did a bit of a light to dark gradient from the top to the bottom. The bend in his left leg gave a big top surface that catches a lot of light. Again I did a subtle gradient from light at the top down to dark, then back to light again at the tip of the knee. Notice the strength of the shadows, how dark they are, varies. Major features get darker shadows than minor ones. And lastly there are small details like the seams. I went over these with the shadow color (Burgundy Wine) and then did a little highlighting along the bottom edge where it would catch the light. Capes, clothing with folds, anything like this are great places to work on your light placement (and blending).