MMMmm...good subject matter, as the design is great.

Im a big Star Wars fan and I can tell you this wrong straight out of the gate...its there feature wise, but it all needs a bit of a move around to get shape and proportions right, try and find as much ref as possible...also watch for the fake helmets..you can tell them a mile off, they look squashed...

Ive got a couple of links here:

https://www.newlaunches.com/entry_ima...t_helmet_1.jpg

https://www.starwarstoymuseum.com/ima...metauction.jpg

https://www.starwarshelmets.com/2007/...per-Helmet.jpg

these should hep you

JAy