I think if you practiced a bit on your perspective and form, those details like hatching and rendering would come a bit easier, as the form is what you will follow with your hatching. There will be some thickness to the helmet a this thickness also helps the perspective and realism. I hope this helps you with some things you can practice and how you can start with simple shapes first.
Thank you for the feedback, the paintover is very helpful and I can immediately see where I can improve and what I should practice. It is much appeciated! :)
Glad I could help. With a little practice you’ll get there in no time! Happy drawing

