Plague Marine w/Plasma Pistol
This is one of the coolest Plague Marine models. It is officially a champion, but since an Average Joe Chaos Space Marine can be armed with a plasma pistol now, I'm thinking of converting up a few more Nurgle guys armed with plasma pistols.
The best part about this model is the face. It has my evil blue color which is actually started with Ghoul Grey and I use Space Wolf Grey for the final highlights. In between I use Moody Blue and some blending generally. I also use thinned down blue washes. The evil blue can take advantage of tiny lines or striations as others call them but I also use edge highlighting and other techniques. Since Ghoul Grey dried out I just start with blue over the black basecoat. I then blend in Space Wolf Grey and use a lot of thinned washes, sometimes using pure white as well. Blue faces are something of an underlying theme of my army. I even painted up seven blue skinned plaguebearers.
I also like the color I came up with for the plasma part of the plasma pistol. Though it is a bit blurry in this picture. It is kinda a fuschia. It differs noticeably from the purple I use for tubing on my Green Plague Marines. Normally I do a mix of red, orange, and yellow for my plasma. It is actually easy to do a good job on the ridged parts of plasma weaponry. You can just paint the ridges a mid-tone then wash it with a darker color and some simple highlights. To do yellow you should first paint it white, if you have primed the model black, yellow does not cover black, neither does orange in my experience. Owen suggested painting brown over black then using orange or red. I used this technique on the Tau helmet on my OOP Terminator Lord I recently repainted.