Here's how I do yellow for my Imperial Fists.
-Prime White
-Paint it with yellow ink. I use Reaper's Lemon Yellow ink from thier pro-paint line.
-Go over the model with Tamyia Orange Clear. Mostly just geting the panel lanes and such.
-Once the orange has dried give it a 'heavy' drybursh of Desert Yellow(another Reaper paint should be close to Golden Yellow)
-Then a light drybursh of Sunlight. (Reaper paint close to Badmoon yellow I think)
-Then hit the yellow with a light wash of yellow ink.
-Add a few white highlights to the very edges of the armor.
I haven't had alot of luck getting the orange clear to work right so I go back over the panel lines and joints with chestnut ink. Basicly brown lineing them.
Somebody else will have to chime in on doing battle damage as I haven't tried it yet.
