Collocations for helmet - noun

leather, metal, plastic, steel, tin (esp. BrE)
protective
full-face, visored
combat, riot
Police in riot helmets lined the streets.

bicycle, bike, crash, cycle (BrE), motorbike (BrE), motorcycle, safety
football, hockey (both AmE)
fireman's, policeman's (both esp. BrE)
horned, Viking
Kevlar™, pith

have on, wear
don, put on
pull off, remove, take off

visor