Anathomy pratice (or not?) maybe someone might see this as offensive... but it is no

[Chris2Balls [:B]]

The biggest version is okay, but the outline on the left just seems too thick and dark... The highlights are fine, as are the proportions. Maybe the cleavage is a bit too round/rounded, it isn't as if she had a bra on.
The first image has too much black in my opinion, and the colours could be more contrasted. The selout with the black doesn't look good, which is why I think you should change the colour of the outline.