I finally got around to airbrushing these guys. I had to check that my compressor wouldn't wake up my son, and thankfully being at the opposite side of the house was sufficient. So that means I can work on things while he's napping or sleeping.
Anyway, I added some highlighting layers to these guys. I'm using Badger minitaire paints, and found that they weren't really adding much until I added some white to the paint. In the future I think I'm going to start with a black base rather than blue and work up the colours. After a blue and white coat I added some blue ghost tint to the models. Some of it helped, but I also think I may have messed up some areas. Maybe I'll give these guys another shot before moving on to brushing on the other colours.