Tom

A good start, but in need of a bit of blocking out still in the proportions I feel. Google Boba Fett Images...theres tons!!! If you are going for a realistic approach, do yourself a favour and dont copy someone elses work such as that video, as the model in the video is far from perfect. He clearly hasnt used references properly.

If you want to see how a Boba Fett Helmet is made full size so you can translate it to 3d, I would suggest joining https://www.thedentedhelmet.com/ its a feast of Boba Fett builders with lots and lots of people building full sized ones. Chances are there are cg builders there too with more and most likely better references than google....

Mesh wise I think you are on track, just get the shapes and froms sorted and then we can refine the mesh...

good luck

Jay