A drawing of a somewhat typical normal helmet. It could be even less pretty and less well made, you know, beaten up and aged. But those really grunt soldier helmets can be copied from the movies easily.
All the modular bits are there - a nasal (there could be the goggles instead too), the eyebrows, optional cheekguards...There isn't a neckguard, but there could be - a leather layered one, or maybe metal hinged one. The crest with the plume is also optional.