I managed to get hold of a Fett helmet and decided to go down the ESB route. Below are progress photos.
Green, red and black painted on.
Photo below of helmet, Light beige applied to back, weathering relief pattern drawn on, then using Winsdsor and Newtons masking fluid the weathered area was masked off. Airbrushed the blue green mixture over beige area with masking fluid, then removed the masking fluid to this.
Below is where I am at now, which is in the process of painting the metal weathering, using the topical method as per Steve the Swedes Tutorial.