This is the best tutorial thread that I am aware of for painting an ESB helmet.
http://www.thedentedhelmet.com/showthread.php?t=4110&highlight=esb+paints
The Rogue Studios Sticky thread at the top of this forum is also full of very useful information.
Im sure members like AFFO$ and SuperJedi will chime in with their expertese because they have painted some incredible ESB buckets.
I have only recently began painting a helmet and having neber done so before, I am too intimidated by the complexity of the ESB at this time. Im using my current project to learn how to paint. My advice, which isn't neccessarily the correct way, just my way of doing things . . is
to get as much refrence material as you can
use the smallest brushes for max detail
allow plenty of time for paint to dry between applications
take your time, the slower you go the better the results.
All the best with your project.