The way i see it, there are 2 aspects to a finished skin. Technical detail, and overall look. A skin can be jammed with detail, but the overall look can be off, or it can be a very low detal skin, but it looks like it fits.
You obviously have the technical detail side down fairly well, but now you have to work on giving your skins a more overall uniform look. For example, if you take the yellow one, were you to take some of the silver areas, and make them black (shoulderpads, forearms/elbow area), it would go a long way to improoving its overall look. As allthough the silver is nice, its very strong contrast, so to much of it can look a bit noisy.
Anyway like i said, its still a lovely skin, im just trying to help you perfect it