Hey there! I see that you're applying warm light/cool shadows (and vice versa), which is a good principle to think about in these studies. Though taking a closer look at the original images, you'll still see this principle being applied, but to a lesser extreme. For example, on the old man, his shadows appear actually more purple/pink. They aren't fully desaturated and cool, but they are still cooler than the base warm tone. Another quick tip, for the black and white image, this is a great way to study the reflectivity of objects. Something metallic, like in this example, has much higher contrast with bright highlights and dark shadows. You show a lot of thought and great choices throughout the assignment, I hope you find these tips useful. Keep up the good work :)

Good job! The only thing I would look over is the value of the top plane of the cube shape. It seems a little too dark.

It looks like he definitely gravitates almost entirely towards soft brushes for this assignment, especially because occlusion shadows are very soft and diffused. However, it does seem like he sometimes uses a harder brush when blocking in the light grey base that goes before any shadows, and uses the lasso tool to provide a hard edge for some shadow crevices before going in with a soft brush.