Oh, man -- I wish I would've found this thread sooner. Now I'm way behind.
IdiotApathy -- you're the man for dedicating so much time and effort to help out your fellow artists.
Okay, exercises 1 and 2:
First thing I notice is that I'm not confident in determining the shape of the form shadow. In particular, how much it kinda creeps around the outside edges...is it more of a C or a ( ?
I've repainted this thing twice now. Started with a hard brush, then switched to a soft one, which I almost never use in general.
I feel like the full light may be a bit too big, but I'm not really sure. I don't want to let the half-light creep up too much, and I also want to limit the basic values.
Realized that my cast shadow was very much for a side-lit type situation, and my form shadow was more of a front-side (diagonal?) type shadow, so I repainted the sphere again.
Not much to say on this one, except that it's hard. Adding color really throws off my perception of values. I did pump up the saturation a bit in the half-light area, reasoning being that it's not washed out by being directly in the light, and now dimmed by being too shadowed. I think I remember this being true, and it seems right to me.
....aaaaaand, lo and behold, total failure. It really looked close to me in color. Oh well, that's how we learn, eh? It looks like the only part I was close on was the reflected light.