Welcome to the project pages Roboknee!
For a first unit Robo, they look great! Orks are great minis to get into painting. You're right, they're very responsive to the Base, Wash, Layer/Drybrush approach to painting.
I think that you're done a great job. The colours look good. Yellow is by far and away the toughest colour to paint well IMHO. Your yellow looks good though. If you wanted to have it retain it's strong vibrancy, as Cav suggested, go for a Seraphim Sepia wash on the yellow bits instead of the, I'm guessing Agrax Earthshade, that you used. Sepia is just a little softer and more complimentary.
Otherwise, great stuff and a cracking start to your Plog!