If this relatively simplistic example gets you going on your hemet, I and others can help walk you through getting the various pieces going for your helmet.
If you need full on tutorial about how to do things, i will have to bow out...
Just make piece by piece and get them put onto your helmet shape.
The mask can be a separate "nudge in the right direction later" .... Most of it is fairly simplistic stuff
For expediency, I just flattened the 3d helmet to get flow to perform. But the way I did it could be called "Bad practice" by making bad geometry. Just success due to simplicity.
I think using a "Sphere" would have been an incorrect starting point. Trying to get a "Base" for flow to match a "target" of sphere because a sphere is a "special type of geometry"
I think I would make my "Sphere" with a different command that would allow me to make my base with the same general structure.... (Or i could cut things in half and only work on half at a time and use the flatten. But I think there are "better" methods to go after...
There are other discussions here regarding this. but OP doesn't need to dive into this to get going....