Airbrush techniques are similiar to those used in the Renaissance. A monochromatic underpainting is a good start. Layering translucent colors over, produces a similiar "deep" effect. You'll often find double imagery in my pieces too.
MasterBeast II fender
Laying down the under painting on the MasterBeast II tank.
Miniature version of tank on 3" primary belt.
Drive belt airbrushing and small pc on rear fender '49 Panhead "El's Diablo"