Thanks for leaving a comment. I decided to use different coloured helmets for different battlefield roles. Fire support marines in my homebrew chapter use gunmetal helmets. On the other hand, the green helmet is used chapter-wide by sergeants. If you're interested, feel free to visit my plog in the WIP subforum.
as I wrote in one post - it is very simple. This is like third fle in my life. I was scared of painting the flames for a long time, but after few tries I can say - it is easy to get a nice looking effect with two contrast paints and a wet blending. Just give it a try
White base, then fluorescent green ink from Liquitex (several coats), then water effect gel (thin) and a little bit more fluorescent green if I remember correctly. In other words - a lot of time spent on waiting for the paint to dry